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Sample records for aluminum garnet laser

  1. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    Science.gov (United States)

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection. PMID:20862016

  2. Comparison of the erbium-yttrium aluminum garnet and carbon dioxide lasers for in vitro bone and cartilage ablation

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, C.; van de Merwe, W.P.; Smith, M.; Reinisch, L. (Uniformed Services Univ. of the Health Sciences, Bethesda, MD (USA))

    1990-01-01

    The in vitro bone- and cartilage-ablation characteristics of the solid-state erbium:yttrium aluminum garnet laser were compared to those of the carbon dioxide laser. Ablations of fresh, frozen cadaver septal cartilage and maxillary sinus bone were performed using total energies between 1 and 6 J. Specimens were studied using hematoxylin and eosin stain and digitized, computer-assisted measurements of 35-mm photographs. Erbium-yttrium aluminum garnet-ablated bone averaged 5 microns of adjacent tissue thermal injury, compared with 67 microns with carbon dioxide-ablated bone. Erbium-yttrium aluminum garnet-ablated cartilage averaged 2 microns of adjacent tissue thermal injury, compared with 21 microns with the carbon dioxide-ablated cartilage. The tissue-ablation characteristics of the erbium-yttrium aluminum garnet laser are promising for future otolaryngologic applications.

  3. Holmium: yttrium-aluminum-garnet (Ho:YAG laser for resection of bladder tumor in a pediatric patient

    Directory of Open Access Journals (Sweden)

    Suleyman Cakmakci

    2015-09-01

    Full Text Available Bladder tumours are rare in children, with only 0.4% of cases occurring in the first 2 decades of life. Herein, a pediatric patient who underwent TUR-B with a holmium: yttrium-aluminum-garnet (Ho:YAG laser is presented. Its histopathology was reported as urothelial papilloma.

  4. Pulsed neodymium: yttrium aluminum garnet laser (532 nm) melting of crystalline silicon: Experiment and theory

    International Nuclear Information System (INIS)

    Time-resolved reflectivity measurements have been used to determine both the time of onset-of-melting and the duration of melting resulting from frequency-doubled neodymium: yttrium aluminum garnet (532 nm) pulsed-laser irradiation of crystalline silicon. Substantially shorter surface melt durations were obtained with increasing energy density E/sub l/ than were reported earlier by others. Thermal melting model calculations, which take into account the temperature-dependent optical and thermal properties of silicon, are in substantial agreement with the observed E/sub l/ dependence of the onset of melting and surface melt duration. Inclusion of intensity-dependent absorption in the modeling further improves this agreement

  5. Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism

    OpenAIRE

    Puri, Neerja

    2015-01-01

    Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminumgarnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Materials and Methods: Thi...

  6. Comparative study of diode laser versus neodymium-yttrium aluminum: garnet laser versus intense pulsed light for the treatment of hirsutism

    OpenAIRE

    Neerja Puri

    2015-01-01

    Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Materials and Methods: Thi...

  7. The use of Erbium: Yttrium-aluminum-garnet laser in cavity preparation and surface treatment: 3-year follow-up.

    Science.gov (United States)

    Buyukhatipoglu, Isil; Secilmis, Asli

    2015-01-01

    From the currently available choices, esthetic restorative materials for posterior teeth are limited to composite and ceramic restoration. Ceramic inlays/onlays are reliable solutions for both of these treatments. For successful treatment planning, usable ceramic and adhesive systems should be chosen by the dentist. Since the Federal Drug Administration approval of the erbium: Yttrium-aluminum-garnet (Er:YAG) laser-for caries removal, cavity preparation and the conditioning of tooth substance-in 1997, there have been many reports on the use of this technique in combination with composite resins. In addition, cavity pretreatment with the Er:YAG laser (laser etching) has been proposed as an alternative to acid etching of enamel and dentin. This case report presents the use of the Er:YAG in cavity preparation for composite resin restoration and surface treatment for ceramic onlay restoration of adjacent permanent molars. PMID:26038665

  8. Endothelial cell study in a case of Werner′s syndrome undergoing phacoemulsification and Yettrium-Aluminum-Garnet laser capsulotomy

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    Vasudha Kemmanu

    2012-01-01

    Full Text Available Werner′s syndrome (WS is a rare autosomal recessive disorder with multisystem manifestations of premature aging from the second decade of life. Cataract is one of the features of WS. Cataract surgery is complicated with postoperative wound dehiscence and bullous keratopathy when the surgery is done by intracapsular or conventional extracapsular method. We report the short-term result of phacoemulsification and Neodymimum Yettrium-Aluminum-Garnet laser (Nd YAG capsulotomy in a case of WS with bilateral cataracts. Postoperatively and post capsulotomy, there was no change in the endothelial cell morphology. There was an 8.6% decrease in endothelial cell count at the end of 15 months postoperatively and 11 months post YAG capsulotomy. This decrease is within the acceptable range of cell loss after phacoemulsification and YAG capsulotomy. To the best of our knowledge, this is the first reported case of YAG laser capsulotomy in WS.

  9. [Treatment of hemangioma with the neodymium:yttrium-aluminum-garnet laser (Nd:YAG laser)].

    Science.gov (United States)

    Werner, J A; Lippert, B M; Godbersen, G S; Rudert, H

    1992-08-01

    Laser therapy and in particular Nd:YAG laser therapy has become of increasing importance amongst the various methods of treating haemangiomas. Nd:YAG laser radiation penetrates deep into the tissue. To avoid undesirable results of treatment, certain treatment guidelines must be observed: to protect the tissue from serious heat damage, the Nd:YAG laser radiation should be applied exclusively with simultaneous tissue cooling. Depending on the location of the haemangioma, this is carried out with ice cubes (if possible, not containing air bubbles) or with an ice-cold Ringer solution. The depth of penetration of the laser radiation can be increased by tissue compression with a piece of ice or with a special glass disc. In very voluminous haemangiomas, the laser light is additionally applied via a bare fibre directly on to the vascular tissue. The laser power densities we use are between 500 and 3,000 watts/cm2. The power chosen depends on the tissue effect of the laser radiation. Blanching of the vascular tissue without carbonisation is aimed at. With consistent observance of the treatment guidelines specified, haemangiomas should be treated as early as possible with the Nd:YAG laser. The treatment principle of "wait and see" is often advocated, but we consider to be obsolete, since cosmetically and functionally unsatisfactory residual scars may remain even after complete haemangioma regression. Moreover, the progressive haemangiomas which often lead to complications cannot be distinguished from regressive haemangiomas. Last but not least, the child and the parents should be spared the (in some cases appreciable) psychological strain of a haemangioma. PMID:1388462

  10. Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

    Science.gov (United States)

    Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

    2014-01-01

    Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG) laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under ×10 magnification and adhesive remnant index (ARI) score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa) was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa) (P = 0.41). There was no significant difference in the ARI scores between two groups (P = 0.08). However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching. PMID:25097641

  11. Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2014-01-01

    Full Text Available Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under Χ10 magnification and adhesive remnant index (ARI score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa (P = 0.41. There was no significant difference in the ARI scores between two groups (P = 0.08. However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching.

  12. Laser-related properties of chromium- and neodymium-doped gadolinium scandium aluminum garnet (Cr:Nd:GSAG)

    Energy Technology Data Exchange (ETDEWEB)

    Sumida, D.S.; Mangir, M.S.; Rockwell, D.A. (Hughes Research Laboratories, 3011 Malibu Canyon Road, M/S RL 65, Malibu, California 90265-4799 (United States)); Shinn, M.D. (Bryn Mawr College, Department of Physics, Bryn Mawr, Pennsylvania 19010-2899 (United States))

    1994-10-01

    The spectroscopic, lasing, and thermal properties of chromium- and neodymium-doped gadolinium scandium aluminum garnet (Cr:Nd:GSAG) are reported. The Judd--Ofelt parameters, radiative lifetime, and branching ratios were determined, and an effective emission cross-section value of 0.92 [times] 10[sup [minus]19][ital cm][sup 2] was derived at 1.06 [mu]m from our spectroscopic measurements. The temporal behavior of the Cr[sup 3+] fluorescence intensity agreed with the Inokuti--Hirayama model for the chromium--neodymium energy-transfer mechanism, which invokes a static dipole--dipole interaction and no migrational energy transfer. Under identical flash-lamp-pumping conditions the measured pumping efficiency of Cr:Nd:GSAG for threshold lasing is nearly equal to the pumping efficiency of codoped gadolinium scandium gallium garnet (Cr:Nd:GSGG). From the threshold-lasing data, an effective emission cross section of 0.7 [times] 10[sup [minus]19] cm[sup 2] for Cr:Nd:GSAG was independently determined, as well as a value of 1.3 [times] 10[sup [minus]19] cm[sup 2] for Cr:Nd:GSGG. The normalized heating parameter [chi], defined as the heat deposited per unit stored energy, experimentally ranges from 2.1 to 2.7, depending on the effective emission cross-section value. Our calculated value of [chi] is 1.9 [plus minus] 0.3. Based on our heating-efficiency measurements, calculated Cr:Nd:GSAG thermal lensing values are [similar to] 2.1--2.6 D/kW, which indicates a thermally induced focal length that is weaker than that of Nd:YAG by approximately a factor of 2 at the same output power. Finally, the benefits and trade-offs of laser-diode pumping are discussed.

  13. Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

    OpenAIRE

    Chembolli Lakshmi; Gayathri Krishnaswamy

    2015-01-01

    Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective int...

  14. Efficacy of the q-switched neodymium: Yttrium aluminum garnet laser in the treatment of blue-black amateur and professional tattoos

    OpenAIRE

    Chembolli Lakshmi; Gayathri Krishnaswamy

    2015-01-01

    Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective int...

  15. Mechanical and metallurgical properties of pulsed neodymium-doped yttrium aluminum garnet laser welding of dual phase steels

    International Nuclear Information System (INIS)

    Highlights: → We found that energy input pattern influence the mechanical properties of dual phase steels. → The longitudinal welded specimen showed higher strength than transverse one. → At higher levels of pulse duration the welded samples showed coarse grains in the heat affected zone. → Increasing the effective peak power density caused an increase in strength of the welded specimens. -- Abstract: In this paper, the effect of energy input pattern in pulsed neodymium-doped yttrium aluminum garnet laser welding on mechanical and metallurgical characteristics of a 0.19% carbon dual phase steel is studied. The experimental results showed that the energy input pattern to the fusion zone had a significant effect on the ultimate tensile strength of the welded samples. The longitudinally and transversely tested weld specimens showed higher and lower strength than the base metal respectively. Increase in effective peak power density increased the volume of fusion zone which in turn caused an increase in the strength of the welded specimens. Microstructural studies showed coarse grains in the heat affected zone of welded samples especially at higher levels of pulse duration. Fracture studies showed presence of dimples on the fractured surfaces of the heat affected zone indicating that a ductile fracture had occurred.

  16. Scintillating properties of rare earth aluminum garnets

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Nikl, Martin; Beitlerová, Alena; Kučera, M.; Nitsch, Karel; Malý, P.; Blažek, K.

    2013-01-01

    Roč. 5, č. 6 (2013), s. 1-3. ISSN 2164-6627 R&D Projects: GA MŠk LA08015; GA ČR GA202/08/0893 Institutional support: RVO:68378271 Keywords : scintillation * aluminum garnets * Ce 3+ and Pr 3+ dopants * light yield * annealing Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. In vitro study of the erbium:yttrium aluminum garnet laser cleaning of root canal by the use of shadow photography

    Science.gov (United States)

    Gregorčič, Peter; Lukač, Nejc; Možina, Janez; Jezeršek, Matija

    2016-01-01

    Erbium:yttrium aluminum garnet laser cleaning is a promising technique in endodontic treatment. In our in vitro study, we measured the vapor-bubble dynamics in the root canal by using shadow photography. The canal model was made of a plastic cutout placed between two transparent glass plates. An artificial smear layer was applied to the glass to study cleaning efficiency. In our results, no shock waves have been observed, since the pulp-chamber dimensions have been in the same range as the maximum diameter of the vapor bubble. This leads to the conclusion that shock waves are not the main cleaning mechanism within our model. However, the cleaning effects are also visible in the regions significantly below the bubble. Therefore, it can be concluded that fluid flow induced by the bubble's oscillations contributes significantly to the canal cleaning. We also proposed a simple theoretical model for cleaning efficiency and used it to evaluate the measured data.

  18. Modulatory effects by neodymium-doped yttrium aluminum garnet laser on fibroblast attachment to single rooted tooth surfaces following ultrasonic scaling and root planning: An in vitro study

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    Shanta Negi

    2015-01-01

    Full Text Available Context: One of the most important goals of periodontal therapy is connective tissue reattachment to previously diseased root surfaces. In the recent years, laser therapy has been considered as an important tool in improving the treatment of periodontal disease. Aims: To evaluate the neodymium-doped yttrium aluminum garnet (Nd: YAG lasers effects on root surfaces affected by periodontal disease and compare this treatment with scaling and root planning (SRP in terms of fibroblast attachment. Materials and Methods: A sample of 30 single-rooted human teeth extracted because of advanced periodontal disease was used in this study. Sixty specimens obtained by longitudinal sectioning were randomly divided in three groups. Group A control (untreated; Group B SRP; Group C laser (Nd: YAG and ultrasonic scaling. All specimens were incubated with fibroblast suspension and then fixed and observed under scanning electron microscope. Results: With a median of 8, the control group (Group A exhibited the least number of total fibroblasts among all the three groups. The laser and scaling - treated group (Group C showed the highest number of fibroblasts (median = 49, mean ± standard deviation [SD] = 48.28 ± 17.18, followed by SRP only (Group B, median = 22, mean ± SD = 22.24 ± 8.67. Conclusions: Nd: YAG laser irradiation at specific energy densities can be used as a useful tool to condition the root surfaces, enhancing fibroblast attachment. Hence aiding in re-establishment of the connective tissue attachment to the root surfaces of previously diseased teeth.

  19. Pupil-occluding organized hyphema anterior to the intraocular lens treated by neodymium: yttrium-aluminum-garnet laser: a case report

    Science.gov (United States)

    Kim, Moosang; Lee, Seung-Jun; Han, Sang Beom; Yang, Hee Kyung; Hyon, Joon Young

    2016-01-01

    We report, to our best knowledge, the first case of treatment of pupil-occluding postoperative organized hyphema anterior to the intraocular lens (IOL) using neodymium: yttrium-aluminum-garnet (Nd:YAG) laser. A 78-year-old Asian female underwent uneventful cataract operation. She had been taking aspirin, which she discontinued 1 week before surgery. Iris prolapse occurred at the end of the surgery, which led to intracameral bleeding. Two weeks later, her best-corrected visual acuity was hand motion. Although hyphema had decreased, pupil-occluding organized hematoma had formed anterior to the IOL. The blood clot anterior to the IOL was removed using Nd:YAG laser. One week later, although the hematoma anterior to the IOL resolved, endocapsular hematoma was observed, which was dispersed with Nd:YAG laser posterior capsulotomy. Two weeks later, her best-corrected visual acuity improved to 20/60. There was no complication associated with Nd:YAG laser. In conclusion, pupil-occluding organized hyphema anterior to the IOL can occur as a complication of cataract surgery, in which Nd:YAG laser can be a useful treatment option. PMID:27462181

  20. A comparative scanning electron microscopy study between hand instrument, ultrasonic scaling and erbium doped:Yttirum aluminum garnet laser on root surface: A morphological and thermal analysis

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    Mitul Kumar Mishra

    2013-01-01

    Full Text Available Background and Objectives: Scaling and root planing is one of the most commonly used procedures for the treatment of periodontal diseases. Removal of calculus using conventional hand instruments is incomplete and rather time consuming. In search of more efficient and less difficult instrumentation, investigators have proposed lasers as an alternative or as adjuncts to scaling and root planing. Hence, the purpose of the present study was to evaluate the effectiveness of erbium doped: Yttirum aluminum garnet (Er:YAG laser scaling and root planing alone or as an adjunct to hand and ultrasonic instrumentation. Subjects and Methods: A total of 75 freshly extracted periodontally involved single rooted teeth were collected. Teeth were randomly divided into five treatment groups having 15 teeth each: Hand scaling only, ultrasonic scaling only, Er:YAG laser scaling only, hand scaling + Er:YAG laser scaling and ultrasonic scaling + Er:YAG laser scaling. Specimens were subjected to scanning electron microscopy and photographs were evaluated by three examiners who were blinded to the study. Parameters included were remaining calculus index, loss of tooth substance index, roughness loss of tooth substance index, presence or absence of smear layer, thermal damage and any other morphological damage. Results: Er:YAG laser treated specimens showed similar effectiveness in calculus removal to the other test groups whereas tooth substance loss and tooth surface roughness was more on comparison with other groups. Ultrasonic treated specimens showed better results as compared to other groups with different parameters. However, smear layer presence was seen more with hand and ultrasonic groups. Very few laser treated specimens showed thermal damage and morphological change. Interpretation and Conclusion: In our study, ultrasonic scaling specimen have shown root surface clean and practically unaltered. On the other hand, hand instrument have produced a plane surface

  1. Skin healing and collagen changes of rats after fractional erbium:yttrium aluminum garnet laser: observation by reflectance confocal microscopy with confirmed histological evidence.

    Science.gov (United States)

    Yang, Jing; Wang, Sha; Dong, Liyun; An, Xiangjie; Li, Yan; Li, Jun; Tu, Yating; Tao, Juan

    2016-08-01

    The fractional erbium:yttrium aluminum garnet (Er:YAG) laser is widely applied. Microstructural changes after laser treatment have been observed with histopathology. Epidermal and dermal microstructures have also been analyzed using reflectance confocal microscopy (RCM). However, no studies have compared these two types of microstructural changes in the same subject at multiple time points after irradiation, and it is unclear if these two types of changes are consistent. We use RCM to observe the effect of different laser energies on skin healing and collagen changes in the skin of Sprague-Dawley rats that had been irradiated by fractional Er:YAG lasering at different energies. RCM was used to observe skin healing and detect collagen changes at different time points. Collagen changes were observed using hematoxylin and eosin (H&E) staining and quantitatively analyzed by western blot. RCM showed that, irrespective of laser energy, microscopic treatment zones (MTZs) were larger at 1 day after irradiation. The MTZs then reduced in size from 3 to 7 days after irradiation. The higher the energy, the larger the MTZ area. The amount of collagen also increased with time from 1 day to 8 weeks. However, the increase in the collagen amount on both RCM and H&E staining was not influenced by the laser energy. Western blotting confirmed that the amount of type I and type III collagens increased over time, but there were no significant differences between the different energy groups (p > 0.05). In conclusion, RCM is a reliable technique for observing and evaluating skin healing and collagen expression after laser irradiation. PMID:27272747

  2. A Comparative Histological Study of Bone Healing in Rat Calvarial Defect Using the Erbium-Doped Yttrium Aluminum Garnet Laser and Rotary Instruments

    Science.gov (United States)

    Jung, Mi-Kyung; Kim, Su-Gwan; Oh, Ji-Su; Jin, Seung-Chan; Lee, Sook-Young; Jang, Eun-Sook; Piao, Zheng-Gang; Lim, Sung-Chul; Jeong, Mi-Ae

    2012-01-01

    Erbium-doped yttrium aluminum garnet (Er:YAG) lasers have been used in dentistry for cutting bone and removal of caries. The purpose of this study was to evaluate the bone healing in a skull defect prepared in rats using various instruments including Er:YAG laser. The 7 mm calvarial defects were created in 45 rats and 45 rats were divided into three groups (n = 15): a high-speed rotation engine with carbide round bur (2-mm diameter), a low-speed rotation engine with carbide round bur (2-mm diameter), and an Er:YAG laser. Specimens obtained after 3 days or 4 or 8 weeks were submitted for histological analysis. Three days after surgery, no bone formation had occurred in any of the groups. Four weeks after surgery, 90 ±8.16% new bone formation was observed in the high-speed group, and 8 weeks after surgery, 100 ±0% new bone formation was observed in the low- and high-speed groups. There were significant differences among the periods after surgery, but no significant differences were observed among final results with in different device groups.

  3. Efficacy and Safety of 120-W Thulium:Yttrium-Aluminum-Garnet Vapoenucleation of Prostates Compared with Holmium Laser Enucleation of Prostates for Benign Prostatic Hyperplasia

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    Kai Hong

    2015-01-01

    Full Text Available Background: This study compared the efficacy and safety between 120-W thulium:yttrium-aluminum-garnet (Tm:YAG vapoenucleation of prostates (ThuVEP and holmium laser enucleation of prostates (HoLEP for patients with lower urinary tract symptoms (LUTS due to benign prostatic hyperplasia (BPH. Methods: A retrospective analysis of 88 consecutive patients with symptomatic BPH was carried out, who underwent either 120-W ThuVEP or HoLEP nonrandomly. Patient demographics and peri-operative and 12-month follow-up data were analyzed with the International Prostate Symptom Score (IPSS, quality of life (QoL score, maximum flow rate (Qmax, postvoid residual urine volume (PVR, and rates of peri-operative and late complications. Results: The patients in each group showed no significant difference in preoperative parameters. Compared with the HoLEP group, patients in the 120-W ThuVEP group required significantly shorter time for laser enucleation (58.3 ± 12.8 min vs. 70.5 ± 22.3 min, P = 0.003, and resulted in a significant superiority in laser efficiency (resected prostate weight/laser enucleation time for 120-W Tm:YAG laser compared to holmium:YAG laser (0.69 ± 0.18 vs. 0.61 ± 0.19, P = 0.048. During 1, 6, and 12 months of follow-ups, the procedures did not demonstrate a significant difference in IPSS, QoL score, Qmax, or PVR (P > 0.05. Mean peri-operative decrease of hemoglobin in the HoLEP group was similar to the ThuVEP group (17.1 ± 12.0 g/L vs. 15.2 ± 10.1 g/L, P = 0.415. Early and late incidences of complications were low and did not differ significantly between the two groups of 120-W ThuVEP and HoLEP patients (P > 0.05. Conclusions: 120-W ThuVEP and HoLEP are potent, safe and efficient modalities of minimally invasive surgeries for patients with LUTS due to BPH. Compared with HoLEP, 120-W ThuVEP offers advantages of reduction of laser enucleation time and improvement of laser efficiency.

  4. Efficacy of the q-switched neodymium: Yttrium aluminum garnet laser in the treatment of blue-black amateur and professional tattoos

    Directory of Open Access Journals (Sweden)

    Chembolli Lakshmi

    2015-01-01

    Full Text Available Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm 2 . The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA and GAS by comparing photographs. Results: After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS and 54.2% (PA improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Conclusion: Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions although this was spaced at longer intervals.

  5. Raman calibration of the HT-7 yttrium aluminum garnet Thomson scattering for electron density measurements

    International Nuclear Information System (INIS)

    A multipulse neodym doped yttrium aluminum garnet laser Thomson scattering system calibrated by the anti-Stokes rotational Raman scattering from nitrogen gas had been developed in the HT-7 superconducting Tokmak. By virtue of this system, measured electron density results of the plasma were obtained. The results showed good repeatability and its total uncertainty was estimated to be ±18%

  6. High-Pressure Optical Studies of Doped Yttrium Aluminum Garnet

    Science.gov (United States)

    Wamsley, Paula

    This thesis demonstrates the application of high pressure spectroscopy to the study of doped insulator laser materials. We investigated transition metal ion and rare -earth ion doped yttrium aluminum garnet (YAG) crystals. Our goal was to explore the relationship between the local bonding environment of the dopant ion and the bulk optical properties of the crystals. Pressure is a useful probe for this type of investigation because pressure changes the local bonding environment of the dopant ion. We conducted laser induced fluorescence experiments and time-resolved laser induced fluorescence experiments on samples in modified Merrill-Basset style diamond anvil cells. We measured the effect of pressure on the laser induced emission of Cr^{3+} and Tm^{3+} in Cr ^{3+}:YAG and Tm^ {3+}:YAG. These experiments provided information about the energy level structure of Cr ^{3+} and Tm^{3+ } as a function of the crystal field strength. In Cr^{3+}:YAG we were able to correlate changes in the emission spectrum to pressure induced changes in the local site-symmetry of the Cr ^{3+} ions. In Tm^ {3+}:YAG we determined that several emission features were incorrectly assigned and observed previously unreported Tm^{3+} emission features. We also measured the time-resolved laser induced emission of Cr^{3+} in Cr^{3+}:YAG and Cr ^{3+}:Tm^{3+ }:YAG. With these measurements we were able to determine the effect of thermal and spin-orbit coupling on the fluorescence properties of Cr^{3+ }. In addition we determined that the fluorescence properties of Cr^{3+} strongly influence the rate of energy transfer and the efficiency of energy transfer from Cr^{3+ } to Tm^{3+} in Cr^{3+}:Tm ^{3+}:YAG.

  7. Obliterated urethra: holmium:yttrium-aluminum-garnet cut-to-light with urolume stenting.

    Science.gov (United States)

    Monga, M; Gordon, Z; Alexandrescu, B

    2001-12-01

    Antegrade-retrograde urethrotomy, or the cut-to-light procedure, performed for obliterated urethra is associated with a high rate of recurrence of urethra] stricture. With the goal of reducing the stricture recurrence rate, we performed a modified cut-to-light procedure using a holmium:yttrium-aluminum-garnet laser and UroLume stenting in a 76-year-old man with urethral obliteration. PMID:11763485

  8. Optical Properties of Irradiated Yttrium Aluminum Garnet

    International Nuclear Information System (INIS)

    The results of investigation of the photoluminescence (PL) and optical absorption of crystals Y3Al5O12(YAG) doped with different concentrations of manganese ions exposed to fast neutron irradiation and electron irradiation are presented. Photoluminescence spectra of YAG before neutron irradiation at T=80 K contain fine lines in orange region of spectrum, ascribed to Mn2+ ions in octahedral position. After irradiation band broadening is observed in the luminescence spectra of garnet crystals. Electron irradiation produced broad band with a complex structure related to Mn4+ ions. Exchange interaction between radiation defect and impurity ions during neutron irradiation and electron irradiation leads to appearance of additional lines and luminescence bands broadening in investigated crystals.

  9. Spectroscopic, thermal, and lasing features of chromium- and neodymium-doped gadolinium scandium aluminum garnet

    International Nuclear Information System (INIS)

    Over the past few years, significant enhancements in lasing efficiency have been well established using chromium sensitizers in neodumium-doped garnets. In particular, Cr:Nd:GSGG has drawn much attention. One characteristic aspect of these gallium garnets is their reduced thermal conductivity. This results in increased effects of heat loading and requires special attention in high average power laser designs. By contrast, Cr:Nd:GSAG, a chromium sensitized neodymium-doped aluminum garnet, possesses an increased thermal conductivity value relative to Cr:Nd:GSGG while yet maintaining an improved pumping efficiency. The authors discuss the thermal handling capability of this material relative to Cr:Nd:GSGG and Nd:YAG and the benefits of its chromium sensitized pumping efficiency based on the presented data. Cr:Nd:GSAG appears to be a promising candidate for many high average power solid state laser applications. Their characterization study of this aluminum garnet in terms of its spectroscopic, thermal, and lasing properties is outlined

  10. Effect of different pre-heat treatment processes on the hardness of AISI 410 martensitic stainless steels surface-treated using pulsed neodymium-doped yttrium aluminum garnet laser

    International Nuclear Information System (INIS)

    Highlights: → The effect of laser surface treatment on the structure of AISI 410 was studied. → The hardness profile was predicted in the sample depth by the finite element simulation. → Laser surface treatment is an effective approach to improve the ferrite hardness. → Laser surface treatment has less positive effects on increasing the martensite hardness. -- Abstract: AISI 410 martensitic stainless steel (MSS) samples were conventionally heat treated in diverse quenching environments to obtain three different microstructures: fine ferrite, fine and coarse martensite. Furthermore, laser surface treatment (LST) was done by pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser to compare the effect of short-term diffusion on the hardness of the different microstructures. The microstructure and microhardness of the samples were investigated by means of an optical microscope and Vickers microhardness tester respectively. Moreover, finite element simulation was done using ABAQUS finite element software to predict cooling curves and temperature histories at different depths of workpiece and to calculate the depth of fully hardened and partially hardened material. A comparison between theoretical and experimental results showed a good conformity and that LST is an effective approach to improve the hardness of the ferrite, despite the coarse and fine martensite phases.

  11. Induction of melasma by 1064-nm Q-switched neodymium:yttrium-aluminum-garnet laser therapy for acquired bilateral nevus of Ota-like macules (Hori nevus): A study on related factors in the Chinese population.

    Science.gov (United States)

    Wang, Ben; Xie, Hong-Fu; Tan, Jun; Xie, Hong-Ju; Xu, Lin-Yong; Ding, Rong; Liu, Fang-Fen; Chen, Xiang; Jian, Dan; Li, Ji

    2016-06-01

    Laser treatment has emerged as a common treatment modality for acquired bilateral nevus of Ota-like macules (ABNOM). To identify the ratio of melasma induction and exacerbation before and after laser therapy for ABNOM and to observe the risk factors related to the induction and exacerbation of melasma by laser therapy, we analyzed related factors of 1268 adult Chinese patients who underwent 1064-nm Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (QNYL) treatment using case series and case-control studies. Overall, 24.0% of the ABNOM patients had mixed melasma. Among the ABNOM patients without melasma, after laser therapy the development of melasma was more frequently noted in patients older than 35 years (P light (similar to yellow-brown) in color (P = 0.021) and skin types were closer to type IV (P < 0.0001). New melasma lesions also appeared most frequently in the zygomatic region (P < 0.0001). Among the ABNOM patients with melasma, 89.5% experienced worsening of their melasma, irrespective of their related factors above. We concluded that the risk of inducing melasma is great after 1064-nm QNYL treatment in ABNOM patients, and particularly in the patients with both ABNOM and melasma. ABNOM patients should be treated as early as possible and before the age of 35 years. PMID:26777390

  12. Cr-SENSITIZED RARE EARTH GARNET LASERS AT ROOM TEMPERATURE

    OpenAIRE

    Huber, G.; Duczynski, E.; Mitzscherlich, P.; Teichmann, H.

    1987-01-01

    We report on fundamental laser properties of Cr-sensitized Nd, Tm, Ho, and Er-garnets as YAG, YSAG, YSGG, GSAG, and GSGG. Due to the Cr- sensibilization the lasers have high efficiencies under laser and flashlamp pumping.

  13. Polycrystalline yttrium aluminum garnet fibers from colloidal sols

    International Nuclear Information System (INIS)

    Polycrystalline yttrium aluminum garnet (YAG) fibers were prepared from commercially available colloidal sols of Y2O3 and AlOOH and water-soluble polymers. The fibers were dry spun and all processing was performed in air. Transformation to YAG was complete by ≅1,300 C, and the fibers were mostly dense by 1,600 C with a final fired diameter of 120 microm. A bend test was used to characterize mechanical strength, and an average of 522±186 MPa with a Weibull modulus of 3.5 was determined. The bend stress relaxation (BSR) test was used to characterize creep properties. The creep resistance was better than that of all commercially available oxide fibers with the exception of Saphikon single-crystal alumina (c-axis oriented). The creep strain of the YAG fibers compared well with that calculated for YAG monoliths with roughly the same grain size

  14. Effects of two erbium-doped yttrium aluminum garnet lasers and conventional treatments as composite surface abrasives on the shear bond strength of metal brackets bonded to composite resins

    Science.gov (United States)

    Sobouti, Farhad; Dadgar, Sepideh; Sanikhaatam, Zahra; Nateghian, Nazanin; Saravi, Mahdi Gholamrezaei

    2016-01-01

    Background: Bonding brackets to dental surfaces restored with composites are increasing. No studies to date have assessed the efficacy of laser irradiation in roughening of composite and the resulted shear bond strength (SBS) of the bonded bracket. We assessed, for the 1st time, the efficacy of two laser beams compared with conventional methods. Materials and Methods: Sixty-five discs of light-cured composite resin were stored in deionized distilled water for 7 days. They were divided into five groups of 12 plus a group of five for scanning electron microscopy (SEM): Bur-abrasion followed by phosphoric acid etching (bur-PA), hydrofluoric acid conditioning (HF), sandblasting, 3 W and 2 W erbium-doped yttrium aluminum garnet laser irradiation for 12 s. After bracket bonding, specimens were water-stored (24 h) and thermocycled (500 cycles), respectively. SBS was tested at 0.5 mm/min crosshead speed. The adhesive remnant index (ARI) was scored under ×10 magnification. SEM was carried out as well. Data were analyzed using analysis of variance (ANOVA), Kruskal–Wallis, Tukey, Dunn, one-sample t-test/Wilcoxon tests, and Weibull analysis (α =0.05). Results: The SBS values (megapascal) were bur-PA (11.07 ± 1.95), HF (19.70 ± 1.91), sandblasting (7.75 ± 1.10), laser 2 W (15.38 ± 1.38), and laser 3 W (20.74 ± 1.73) (compared to SBS = 6, all P = 0.000). These differed significantly (ANOVA P = 0.000) except HF versus 3 W laser (Tukey P > 0.05). ARI scores differed significantly (Kruskal–Wallis P = 0.000), with sandblasting and 2 W lasers having scores inclined to the higher end (safest debonding). Weibull analysis implied successful clinical outcome for all groups, except for sandblasting with borderline results. Conclusion: Considering its high efficacy and the lack of adverse effects bound with other methods, the 3 W laser irradiation is recommended for clinical usage. PMID:26998473

  15. An in vitro evaluation of the responses of human osteoblast-like SaOs-2 cells to SLA titanium surfaces irradiated by erbium:yttrium-aluminum-garnet (Er:YAG) lasers.

    Science.gov (United States)

    Ayobian-Markazi, Nader; Fourootan, Tahereh; Zahmatkesh, Atieh

    2014-01-01

    Erbium:yttrium-aluminum-garnet (Er:YAG) laser treatment is an effective option for the removal of bacterial plaques. Many studies have shown that Er:YAG lasers cannot re-establish the biocompatibility of titanium surfaces. The aim of this study was to evaluate the responses of the human osteoblast-like cell line, SaOs-2, to sand-blasted and acid-etched (SLA) titanium surface irradiation using different energy settings of an Er:YAG laser by examining cell viability and morphology. Forty SLA titanium disks were irradiated with an Er:YAG laser at a pulse energy of either 60 or 100 mJ with a pulse frequency of 10 Hz under water irrigation and placed in a 24-well plate. Human osteoblast-like SaOs-2 cells were seeded onto the disks in culture media. Cells were then kept in an incubator with 5% carbon dioxide at 37 °C. Each experimental group was divided into two smaller groups to evaluate cell morphology by scanning electron microscope and cell viability using 3-4,5-dimethylthiazol 2,5-diphenyltetrazolium bromide test. In both the 60 and the 100 mJ experimental groups, spreading morphologies, with numerous cytoplasmic extensions, were observed prominently. Similarly, a majority of cells in the control group exhibited spreading morphologies with abundant cytoplasmic extensions. There were no significant differences among the laser and control groups. The highest cell viability rate was observed in the 100 mJ laser group. No significant differences were observed between the cell viability rates of the two experimental groups (p = 1.00). In contrast, the control group was characterized by a significantly lower cell viability rate (p Treatments with an Er:YAG laser at a pulse energy of either 60 or 100 mJ do not reduce the biocompatibility of SLA titanium surfaces. In fact, modifying SLA surfaces with Er:YAG lasers improved the biocompatibility of these surfaces. PMID:23179305

  16. Thermal conductivity of garnet laser crystals

    Science.gov (United States)

    Wang, B. S.; Jiang, H. H.; Zhang, Q. L.; Yin, S. T.

    2008-03-01

    The thermal conductivities of nine different synthetic garnet laser crystals at various temperatures, range from 273 to 393 K have been investigated by instantaneous measurement method. The results show that the thermal conductivity of each crystal decreases exponentially with the temperature increasing. It is notable that, different host crystals, such as YAG, GGG, and GSGG have different thermal conductivity, which is attributed to the crucial influence of crystal structure and composition on the absolute value of their thermal conductivity. Moreover, with respect to the same host crystals, the impurity scattering also results in the change of their thermal conductivities. This is because that a higher concentration of doped ions leads to a more phonon scattering modes, which results in a shorter mean free path of the phonons and a lower thermal conductivity. In addition, different host crystals have various dependences of thermal conductivity on dopant concentration. This works provides reliable and useful information for designing high power, high quality, and high stability laser devices.

  17. Thermal conductivity of synthetic garnet laser crystals

    Science.gov (United States)

    Wang, B. S.; Jiang, H. H.; Zhang, Q. L.; Yin, S. T.

    2007-07-01

    The thermal conductivities of nine different synthetic garnet laser crystals at various temperatures, range from 273 to 393K have been investigated by instantaneous measurement method. The results show that the thermal conductivity of each crystal decreases exponentially with the temperature increasing. It is notable that, different host crystals, such as YAG, GGG, and GSGG have different thermal conductivity, which is attributed to the crucial influence of crystal structure and composition on the absolute value of their thermal conductivity. Moreover, with respect to the same host crystals, the impurity scattering also results in the change of their thermal conductivities. This is because that a higher concentration of doped ions leads to a more phonon scattering modes, which results in a shorter mean free path of the phonons and a lower thermal conductivity. In addition, different host crystals have various dependences of thermal conductivity on dopant concentration. This works provides reliable and useful information for designing high power, high quality, and high stability laser devices.

  18. Efficiency of ablative fractional Er: YAG (Erbium: Yttrium-Aluminum-Garnet laser treatment of epidermal and dermal benign skin lesions: A retrospective study

    Directory of Open Access Journals (Sweden)

    Erol Koç

    2014-03-01

    Full Text Available Background: Er: YAG lasers are precise ablation systems used in the treatment epidermal and dermal benign skin lesions. In this study, we restrospectively analysed efficiency of Er: YAG laser therapy in the treatment of epidermal and dermal benign skin lesions. Materials and Methods: We retrospectively investigated our clinical records of 116 patients treated with Er: YAG laser between April 2011 and April 2013. The clinical records of 103 patients (47 men, 56 women were included in our study. Of these 103 patients included in the study were xanthelasma, solar lentigo, epidermal nevus, seborrheic keratosis, nevus of ota, syringoma, cafe au lait macules (CALM and other than these. Treatment parameters, demographic features and before and after photographs of the lesions were investigated from patients’ records in order to evaluate efficiency of Er: YAG laser therapy. Results: Of these 103 patients included in the study were evaluated in 8 groups, described as xanthelasma (n=21, syringoma (n=17, solar lentigo (n=16, epidermal nevus (n=11, seborrheic keratosis (n=9, nevus of ota (n=5, CALM (n=3 and other than these (n=21. In the Er: YAG laser treatment, the average energy flow was 3-7 J/cm2, the average pulse duration was 300 ms, the average number of passes was 3-5 repeat, and the average pulse frequency was 3-7 Hz. While 4.9% of the patients showed no improvement, 59.2% showed marked improvement, 26.2% showed moderate improvement and 9.7% showed mild improvement. Treatment responses in xanthelasma, syringoma, epidermal nevus, solar lentigo and CALM lesions were statistically significant. Observed side effects were hyperpigmentation in 4 patients, hypopigmentation in 3 patients, hypertrophic scar in 2 patients and persistent erythema in one patient and the treatment was well tolerated by all the patients. Conclusion: Er: YAG laser is an effective and safe treatment option in the treatment of benign skin lesions especially in epidermal lesions.

  19. Nd:YAG激光治疗急性局限性智齿冠周炎的临床观察%Clinical observation on treatment of acute wisdom tooth pericoronitis with neodymium:Yttrium-Aluminum-garnet Laser

    Institute of Scientific and Technical Information of China (English)

    栗洪师; 李冬霞; 柯杰

    2015-01-01

    目的:观察口腔钕激光(neodymium:yttrium-aluminum-garnet,Nd:YAG)治疗急性局限性智齿冠周炎的临床疗效。方法:选取114例急性局限性智齿冠周炎患者,局部用3%过氧化氢和生理盐水交替冲洗后棉球擦干,随机分为3组,A组Nd:YAG激光组(n=38):Nd:YAG激光低强度治疗(LLLT)模式,具体选择参数:MSP,1.5 W,100 mJ,15 Hz,非接触局部移动照射病变区肿胀软组织10 min,B组(n=38):局部肿胀龈袋注人适量盐酸米诺环素软膏1次;C组(n=38):局部龈袋置入2%碘甘油,1次/d×3 d。所有治疗组均未全身用药,第4 d观察疗效。结果:和C组比较,A,B组局部炎性肿胀症状均有明显改善,总有效率分别为89.47%和78.95%,A,B两组间疗效无显著性差异(P>0.05)。 A, B组的疗效均显著好于C组(P<0.01;P<0.05.);与B,C组比较,A组患者自觉疼痛明显减轻(P<0.01)。结论:Nd:YAG激光治疗急性局限性智齿冠周炎具有较好临床疗效。%Objective:To study the efficacy of neodymium:yttrium- aluminum-garnet laser of curing acutewisdom tooth pericoronitis,comparing with iodine glycerine. Method:57 cases of acute wisdom tooth pericoronitis were selected and randomly separated into 3 groups,whose local parts were washed with 3 % hydrogen peroxide,and physiological saline consecutively,and dried clearly. For patients in group A test sides were treated with the Nd:YAG laser(1064 nm,MSP,1.5 W,100 mJ,15 Hz). Clinical assessments (total effective rate of local treatment and visual analog scale of pain) were performed pre-treatment and at 4 days post treatment,B,minocycline hydrochloride ointment was injected on their infected areas once. Patients in Group C were treated with 2%iodine glycerine once everyday in 3 days. Efficacy of all experimental treatments were observed at the 4th day. Result:The symptoms of group A an

  20. Fabrication of GaN-Based White Light-Emitting Diodes on Yttrium Aluminum Garnet-Polydimethylsiloxane Flexible Substrates

    OpenAIRE

    Lung-Chien Chen; Wen-Wei Lin; Jun-Wei Chen

    2015-01-01

    This study concerns the characteristics of white GaN-based light-emitting diode (LED) on flexible substrates. The thin film GaN-based blue LEDs were directly transferred from sapphire onto the flexible polydimethylsiloxane (PDMS) substrates by laser lift-off (LLO) process. The PDMS substrates were incorporated 10–40% cerium doped yttrium aluminum garnet phosphor, YAG:Ce3+, and formed the GaN-based white LEDs. The white LEDs prepared by the GaN-based LEDs on the YAG-PDMS substrates reveal one ...

  1. KINETICS OF GRAIN-GROWTH OF YTTRIUM ALUMINUM GARNET FIBERS PREPARED BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Tan H.

    2013-12-01

    Full Text Available The yttrium aluminum garnet (YAG long fibers were prepared by the sol-gel method using aluminum chloride, aluminum powder, yttrium oxide and acetic acid as raw materials. The grain growth law is given by Dn – D0n = Kt (D0 = initial grain size, D = average grain size at time t, n = grain growth exponent and K = reaction constant. The grain growth exponent and activation energy of YAG fibers are ≈ 3 and 200 kJ/mol, respectively. The grain-growth behaviors of YAG were influenced by experimental conditions such as raw materials, initial particle size, initial particle distribution, etc.

  2. Luminescence Properties of Ce3 +-Doped Terbium Aluminum Garnet Phosphor Prepared with Use of Nanostructured Reagents

    OpenAIRE

    I.V. Berezovskaya; B.I. Zadneprovski; N.I. Poletaev; Yu.A. Doroshenko; N.P. Efryushina; E.V. Zubar; V.P. Dotsenko

    2013-01-01

    The paper describes the synthesis of Ce3 +-doped terbium aluminum garnet (TAG) phosphors with use of nanostructured oxides of aluminum and rare earths. Aluminum oxide nanoparticles were obtained by gaseous-disperse synthesis and characterized by X-ray diffraction, differential thermal analysis and scanning electron microscopy. It was shown that the Ce3 + ions in TAG exhibit the intense broad band emission with a maximum at about 563 nm and the quantum efficiency of luminescence of the Тb3(1 –...

  3. Structural and magnetic properties of yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrites prepared by microemulsion method

    Science.gov (United States)

    Akhtar, Majid Niaz; Bakar Sulong, Abu; Khan, Muhammad Azhar; Ahmad, Mukhtar; Murtaza, Ghulam; Raza, M. R.; Raza, R.; Saleem, M.; Kashif, M.

    2016-03-01

    Yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrite samples were synthesized by microemulsion method. The effect of sintering was examined by heating the samples at 900, 1000, and 1100 °C. The YIG and YAIG samples were then characterized using X-ray diffraction and field-emission scanning electron microscopy. Static and dynamic magnetic properties were measured by evaluating initial permeability, Q factor, and vibrating sample magnetometry properties of YIG and YAIG samples. YIG samples sintered at 1100 °C showed higher initial permeability and Q factor compared with YAIG samples. However, hysteresis loops also showed variations in the saturation magnetization, remanence, and coercivity of YIG and YAIG samples sintered at 900, 1000, and 1100 °C. The observed magnetic parameter such as saturation magnetization, coercivity and initial permeability are strongly affected by increasing temperature. The saturation magnetization and coercivity of YIG and YAIG nanoferrites were found in the range 11.56-19.92 emu/g and 7.30-87.70 Oe respectively. Furthermore, the decreasing trends in the static and magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. Thus, YIG and YAIG sintered at 1100 °C can be used for wide-ranging frequency applications.

  4. Crystal field and magnetism with Wannier functions: Rare-earth doped aluminum garnets

    OpenAIRE

    Mihokova, Eva; Novak, Pavel; Laguta, Valentin V.

    2015-01-01

    Using the recently developed method we calculate the crystal field parameters in yttrium and lutetium aluminum garnets doped with seven trivalent Kramers rare-earth ions. We then insert calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determine the multiplet splitting by the crystal field as well as magnetic $\\hat{g}$ tensors. We compare calculated results with available experimental data.

  5. Dislocation of polyfocal full-optics accommodative intraocular lens after neodymium-doped yttrium aluminum garnet capsulotomy in vitrectomized eye

    Directory of Open Access Journals (Sweden)

    Kyung Tae Kang

    2013-01-01

    Full Text Available We report a case of dislocation of WIOL-CF® polyfocal full-optics intraocular lens (IOL after neodymium-doped yttrium aluminum garnet (Nd: YAG laser capsulotomy in the vitrectomized eye. At 22 months before the dislocation of the IOL, a 55-year-old male patient underwent phacoemulsification with WIOL-CF® IOL implantation in a local clinic and 10 months after the cataract surgery the patient underwent pars plana vitrectomy, endolaser photocoagulation and 14% C 3 F 8 gas tamponade for the treatment of rhegmatogenous retinal detachment. At 9 months after the vitrectomy, the patient visited our clinic for a sudden decrease of vision after Nd: YAG capsulotomy in the local clinic. On fundus examination, the dislocated IOL was identified and the Nd: YAG capsulotomy site and the larger break, which is suspected to have been a route of the dislocation were observed in the posterior capsule.

  6. Luminescence Properties of Ce3 +-Doped Terbium Aluminum Garnet Phosphor Prepared with Use of Nanostructured Reagents

    Directory of Open Access Journals (Sweden)

    I.V. Berezovskaya

    2013-03-01

    Full Text Available The paper describes the synthesis of Ce3 +-doped terbium aluminum garnet (TAG phosphors with use of nanostructured oxides of aluminum and rare earths. Aluminum oxide nanoparticles were obtained by gaseous-disperse synthesis and characterized by X-ray diffraction, differential thermal analysis and scanning electron microscopy. It was shown that the Ce3 + ions in TAG exhibit the intense broad band emission with a maximum at about 563 nm and the quantum efficiency of luminescence of the Тb3(1 – xCe3xAl5O12 (х = 0.03 phosphor was found as high as 0.83.

  7. Towards a greater understanding of hydrothermally grown garnets and sesquioxide crystals for laser applications

    Science.gov (United States)

    Moore, Cheryl Ann

    The hydrothermal method of crystal growth offers many benefits over traditional melt-based techniques such as lower temperature requirements relieving detrimental high temperature effects such as stress fracturing and a closed-environment, which limits impurities. The continued study of this type of growth including hydrothermal epitaxy is crucial in our world of constant miniaturization. Presented in this thesis is the hydrothermal growth of crystals of LuAG and Lu2O3 doped with a variety of dopants. Their room-temperature and cryogenic absorption spectra are also presented. Much like Nature uses heat, pressure, water and a nutrient-rich feedstock we have used this hydrothermal technique to produce synthetic crystals of grossular, Ca3Al2(SiO4)3, a naturally occurring garnet as well as other aluminosilicates related to grossular, including a new type of vesuvianite. Other garnets important to the laser industry have also been grown using the hydrothermal technique, such as yttrium aluminum garnet (YAG), lutetium aluminum garnet (LuAG) and the related sesquioxide Lu2O3, (lutetia). The growth and characteristics of Yb-doped lutetia and LuAG, Nd-doped lutetia, and Dy-doped lutetia and YAG are presented herein. These laser crystals have been analyzed by high-resolution absorption spectroscopy at room temperature as well as 250K, 200K, 150K and 80K and absorption coefficients are presented. A coprecipitation technique common in the ceramics field has been adapted for use creating precursors for hydrothermal crystal growth, including phase-pure polycrystalline anorthite and phase-pure gehlenite. Coprecipitation has also been utilized to gain greater control of dopants to create pre-doped feedstocks used for the growth of laser crystal. The versatility of the hydrothermal growth method is also highlighted in a novel epitaxial technique, core growth, which coats the internal surfaces of a seed crystal as well as external surfaces. This can result in multifunctional

  8. Crystal field and magnetism with Wannier functions:rare-earth doped aluminum garnets

    Institute of Scientific and Technical Information of China (English)

    Eva Mihóková; Pavel Novák; Valentin V. Laguta

    2015-01-01

    Using the recently developed method we calculated the crystal field parameters in yttrium and lutetium aluminum garnets doped with seven trivalent Kramers rare-earth ions. We then inserted calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determined the multiplet splitting by the crystal field as well as magneticĝ tensors. We compared calculated results with available experimental data. Very good agreement with the spectro-scopic data and qualitative agreement with experimentalĝ tensors was found.

  9. Infrared to visible up-conversion in thulium and holmium doped lutetium aluminum garnet

    International Nuclear Information System (INIS)

    We report on the up-converted emissions at 367, 458 and 483 nm in thulium doped lutetium aluminum garnet (LuAG) under infrared excitation in the range of 730-800 nm. We also observe blue and strong green emission in thulium and holmium codoped LuAG with near infrared excitation. Excitation spectra, power dependence, temporal behavior and temperature dependence of up-converted emissions were measured to explain the up-conversion mechanisms. Several cross-relaxation mechanisms and excited state absorption are found to be responsible for the observed up-conversion processes

  10. Upconversion luminescence in Yb{sup 3+}-doped yttrium aluminum garnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiaodong [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China) and Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: xdxu79@yahoo.com.cn; Zhao Zhiwei [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China)]. E-mail: zzw@mail.siom.ac.cn; Song Pingxin [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Jiang Benxue [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Guoqing [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China); Xu Jun [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China); Deng Peizhen [Crystal Centre, Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai 201800 (China); Bourdet, Gilbert [Laboratoire pour l' Utilisation des Lasers Intenses, UMR7605, CNRS-CEA-Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Christophe Chanteloup, Jean [Laboratoire pour l' Utilisation des Lasers Intenses, UMR7605, CNRS-CEA-Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Zou, Ji-Ping [Laboratoire pour l' Utilisation des Lasers Intenses, UMR7605, CNRS-CEA-Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Fulop, Annabelle [Laboratoire pour l' Utilisation des Lasers Intenses, UMR7605, CNRS-CEA-Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2005-03-15

    In this paper, we present results on upconversion luminescence performed on Yb{sup 3+}-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb{sup 3+} cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb{sup 3+} energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  11. Computational modelling of Er(3+): Garnet laser materials

    Science.gov (United States)

    Spangler, Lee H.

    1994-12-01

    The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

  12. Sol-gel Synthesis and Characterisation of NanocrystallineYttrium Aluminum Garnet Nanopowder

    Directory of Open Access Journals (Sweden)

    Kiranmala Devi

    2008-07-01

    Full Text Available The synthesis of  yttrium aluminum garnet (YAG (Y3 Al5O12 nanopowder was carried outby sol-gel method. Y(NO33.6H2O, Al(NO33.9H2O in the presence of citric acid as complexing agent were used as starting materials. YAG nanopowder was characterised by FTIR, TGA, andXRD. To get phase-pure nanocrystalline YAG powder at relatively lower temperature, calcinationat various temperatures was studied and calcination temperature was optimised. Particle size,estimated by XRD using Scherrer's equation, was found to be 28Œ35 nm which was further confirmed by transmission electron microscopy. The particle morphology was studied by SEM.Defence Science Journal, 2008, 58(4, pp.545-549, DOI:http://dx.doi.org/10.14429/dsj.58.1675

  13. Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

    International Nuclear Information System (INIS)

    Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluate roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency

  14. Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guojian; Lou, Chaogang; Kang, Jian; Zhang, Hao [School of Electronic Science and Engineering, Southeast University, Nanjing 210096, Jiangsu Province (China)

    2015-12-21

    Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluate roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency.

  15. Fine Structure of the R Absorption Lines of Cr3+ in Antiferromagnetic Dysprosium Aluminum Garnet

    Science.gov (United States)

    Aoyagi, Kiyoshi; Kajiura, Masako; Sugano, Satoru

    1981-11-01

    The absorption spectrum of a Cr3+ ion in an antiferromagnetic disprosium aluminum garnet with the Néel temperature TN of 2.5 K, is measured in the red region between 1.7 K and 4.2 K. It is shown that the fine structure of the R1 and R2 lines at 1.7 K can be explained by using an effective Hamiltonian for the t2g3 2E excited state of Cr3+ in the surrounding of the ordered Dy3+ spins. The gross feature of the observed temperature dependence of the fine structure is shown to be reproduced by assuming appropriate exchange interactions of Cr3+ with Dy3+.

  16. Grain growth and microstructural evolution of yttrium aluminum garnet nanocrystallites during calcination process

    International Nuclear Information System (INIS)

    An yttrium aluminum garnet (YAG) precursor precipitate was synthesized by urea method using yttria (Y2O3) and aluminum nitrate (Al(NO3)3.9H2O) as raw materials. The fresh wet precipitate was dried by supercritical carbon dioxide (CO2) fluid and the resulting powder was calcined at temperatures from 600 to 1600 oC. Crystallization of YAG was detected at 800 oC, and completed at 900 oC. HRTEM images of the YAG product obtained above 900 oC revealed crystallographically specific oriented attachment along the [1 1 2] direction. Based on the observation of the particle morphology a possible growth mechanism of YAG nanoparticles was presented. The fast increase on the average crystallite size of YAG at temperatures from 900 to 1300 oC is attributed to the crystallographically specific oriented attachment growth process. As the growth process proceeds at higher temperatures, oriented attachment based growth becomes less important because of the increase on particle size, and the self-integration assisted by the Ostwald ripening becomes dominant.

  17. Preparation of neodymium-doped yttrium aluminum garnet powders and fibers

    Institute of Scientific and Technical Information of China (English)

    R.López; J.Zárate; E.A.Aguilar; J.Mu(n)oz-Salda(n)a

    2008-01-01

    Using nitrate precursors, a novel spray-drying assisted citrate gel process for the preparation of neodymium-doped yttrium alumi-num garnet (YAG) phase was developed. Synthesis of single-phase polycrystalline YAG was achieved at temperatures as low as 800 ℃ us-ing the spray-drying methodology whilst conventional approaches currently available require 1000 ℃. Initially, a solution was prepared by mixing aluminum and yttrium nitrates, citric acid, etilenglycol and neodymium oxide. This solution was dried by pulverization (spray dryer) to obtain aggregated precursor powders of the compound. These aggregates were calcined at 800, 850 and 900 ℃ to determine the phase evolution from amorphous to crystalline by X-ray diffraction (XRD). The morphology of aggregates was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, through XRD it was determined that the crystallization of YAG phase started at about 800 ℃ without any intermediate phases. The powders were composed of spherical aggregates with an average diame-ter of 1 μm. From these powders, ceramic fibers with additions of 2at.% and 5at.% Nd, were extracted from the melt with diameters ranging from 30 μm to 50 μm.

  18. Luminescence properties and electronic structure of Ce3+-doped gadolinium aluminum garnet

    International Nuclear Information System (INIS)

    Highlights: • The luminescence properties of Ce3+ ions in (Y, Gd)3Al5O12 are analyzed. • The Gd3+ → Y3+ substitution leads to increasing of Ce3+ noncubic crystal field splitting parameter. • The excitation spectra for the Ce3+ emission in GdAG contain bands at 6.67, 7.75, and 9.76 eV. • These features are due to the Ce3+-bound exciton formation and O 2p → Al 3s, 3p transitions. • Contributions from Al atoms to the conduction-band density of states are quite essential. - Abstract: Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce3+ ions have been prepared by co-precipitation method. The luminescent properties of Ce3+ ions in Gd3(1−x)Ce3xAl5O12 (x = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd3+ for Y3+ in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f → 5d excitation bands of Ce3+ ions, the excitation spectra for the Ce3+ emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce3+-bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd3Al5O12, contributions from Altetr and Aloct atoms to the conduction-band density of states are evaluated as quite essential

  19. Structure modification of yttrium iron garnets under the influence of a laser irradiation

    International Nuclear Information System (INIS)

    Magnetoelectric properties of yttrium iron garnets have been investigated by using of the high -sensitive optical polarimetry method - electromagneto-optical effect. We have found out, that irradiation of yttrium iron garnet films by powerful laser impulse leads to essential increase of the electromagneto-optical effect value that can be a result of removal, in them, of local mechanical strain or nonuniform pressure. (authors)

  20. Comparison of Micro-Leakage from Resin-Modified Glass Ionomer Restorations in Cavities Prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) Laser and Conventional Method in Primary Teeth

    OpenAIRE

    Bahrololoomi, Zahra; Razavi, Forooghosadat; Soleymani, Ali Asghar

    2014-01-01

    Introduction: In recent years, significant developments have been taking place in caries removal and cavity preparation using laser in dentistry. As laser use is considered for cavity preparation, it is necessary to determine the quality of restoration margins. Glass ionomer cements have great applications for conservative restoration in the pediatric field. The purpose of this in vitro study was to compare resin-modified glass ionomer restorations micro-leakage in cavities prepared by Er:YAG...

  1. Effects of two erbium-doped yttrium aluminum garnet lasers and conventional treatments as composite surface abrasives on the shear bond strength of metal brackets bonded to composite resins

    OpenAIRE

    Sobouti, Farhad; Dadgar, Sepideh; Sanikhaatam, Zahra; Nateghian, Nazanin; Saravi, Mahdi Gholamrezaei

    2016-01-01

    Background: Bonding brackets to dental surfaces restored with composites are increasing. No studies to date have assessed the efficacy of laser irradiation in roughening of composite and the resulted shear bond strength (SBS) of the bonded bracket. We assessed, for the 1st time, the efficacy of two laser beams compared with conventional methods. Materials and Methods: Sixty-five discs of light-cured composite resin were stored in deionized distilled water for 7 days. They were divided into fi...

  2. Laser ceramic materials for subpicosecond solid-state lasers using Nd3+-doped mixed scandium garnets.

    Science.gov (United States)

    Okada, Hajime; Tanaka, Momoko; Kiriyama, Hiromitsu; Nakai, Yoshiki; Ochi, Yoshihiro; Sugiyama, Akira; Daido, Hiroyuki; Kimura, Toyoaki; Yanagitani, Takagimi; Yagi, Hideki; Meichin, Noriyuki

    2010-09-15

    We have successfully developed and demonstrated broadband emission Nd-doped mixed scandium garnets based on laser ceramic technology. The inhomogeneous broadening of Nd(3+) fluorescence lines results in a bandwidth above 5 nm that is significantly broader than that for Nd:YAG and enables subpicosecond mode-locked pulse durations. We have also found the emission cross section of 7.8 × 10(-20) cm(2) to be adequate for efficient energy extraction and thermal conductivity of 4.7 W/mK from these new Nd-doped laser ceramics. The new laser ceramics are good candidates for laser host material in a diode-pumped subpicosecond laser system with high efficiency and high repetition rate. PMID:20847774

  3. Rare-earth antisites in lutetium aluminum garnets: influence on lattice parameter and Ce.sup.3+./sup. multicenter structure

    Czech Academy of Sciences Publication Activity Database

    Przybylińska, H.; Wittlin, A.; Ma, C.G.; Brik, M.G.; Kamińska, A.; Sybilski, P.; Zorenko, Yu.; Nikl, Martin; Gorbenko, V.; Fedorov, A.; Kučera, M.; Suchocki, A.

    2014-01-01

    Roč. 36, č. 9 (2014), s. 1515-1519. ISSN 0925-3467 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : garnets * scintillators * laser materials * phosphors Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.981, year: 2014

  4. Creep of polycrystalline yttrium aluminum garnet (YAG) at elevated temperature in air and in steam

    International Nuclear Information System (INIS)

    Compressive creep of high-purity polycrystalline yttrium aluminum garnet (YAG, Y3Al5O12) was investigated at 1300 °C and 50–200 MPa in air and in steam. Compressive creep behavior of silica-doped polycrystalline YAG (Y3Al5O12–0.14 wt% SiO2) was also studied. Creep specimens were microstructurally characterized by optical microscopy and TEM before and after creep. Steam slightly increased creep rates of material with grain size less than 1 μm (the undoped YAG), but otherwise had little effect. The flow stress exponent was n≈1 for both SiO2-doped YAG and undoped YAG. Creep rates and microstructural observations are consistent with the Nabarro-Herring creep mechanism, with creep rate limited by lattice diffusion of yttrium cations (Y3+). Silica-doped YAG had a larger grain size of 2.41 μm and lower creep rates than undoped YAG with 0.92 μm grain size. However, creep rates normalized by grain size for Nabarro-Herring creep were higher in SiO2-doped YAG. Possible effects of SiO2 doping and steam on creep of YAG are discussed

  5. Use of the selected overlap LIDAR experiment (SOLEX) system with the 248 nm krypton fluoride and the 355 nm neodymium:yttrium aluminum garnet lasers for the calibration of LIDAR systems for water vapor determination

    Science.gov (United States)

    Mensah, Francis Emmanuel Tofodji

    Water vapor is one of the most important atmospheric variables that play a key role in air quality, global warming, climate change and hurricane formation. In this dissertation, use was made of two laser systems, the 248-nm KrF laser and the 355 nm Nd-YAG laser, with the use of Raman scattering to measure water vapor in the atmosphere. These two systems have been calibrated more accurately, using the LIDAR approach named SOLEX (Selected Overlap LIDAR Experiment). All the experiments were carried out at the Howard University Beltsville campus located on a 107 acre research site, at Beltsville, MD, 15 miles from downtown Washington DC, near the National Agricultural Research Center (NARC), and the NASA Goddard Space Flight Center (GSFC). The geographical coordinates are: 39°04.01'N latitude, and 76°52.31'W longitude. The receiver system used during these experiments is a 30" (76.2 cm), f/ 9 Cassegranian telescope, while the detector system uses a prism spectrometer (Beckman), with a 2-meter, double-fold optical path and a variable slit width is placed at the image plane of the telescope. With the use of the SOLEX system, this dissertation provides an accurate calibration of the two LIDAR Systems for water vapor measurement in the troposphere at the following ranges: 83.7 ft, 600 ft, 800 ft, 1000 ft and 1080 ft. Data analysis shows a pretty high sensitivity of the LIDAR system for water vapor measurement and the efficiency of the SOLEX method.

  6. Diode-pumped garnet crystal waveguide structures fabricated by pulsed laser deposition

    OpenAIRE

    May-Smith, T.C.; Wang, J.; Mackenzie, J.I.; Shepherd, D.P.; EASON, R. W.

    2006-01-01

    We report progress with diode-pumping of garnet crystal waveguide structures fabricated by PLD. Lasing has been achieved in a single-layer Nd:GGG film, and a four-layer structure with a Nd:GSGG core is currently undergoing laser trials.

  7. Fabrication of independent nickel microstructures with anodizing of aluminum,laser irradiation, and electrodeposition

    Institute of Scientific and Technical Information of China (English)

    T. Kikuchi; M. Sakairi; H. Takahashi

    2003-01-01

    Independent microstructures made of Ni metal were fabricated by five sequential processes: porous anodic oxide film for-mation, pore sealing, laser irradiation, Ni electroplating, and removal of the aluminum substrate and anodic oxide films. Aluminumplates and rods were anodized in an oxalic acid solution to form porous type anodic oxide films, and then immersed in boiling dis-tilled water for pore sealing. The anodized and pore-sealed specimens were irradiated with a pulsed neodymium-doped yttrium alu-minum garnet (Nd-YAG) laser beam in a Ni plating solution to remove anodic oxide film locally by rotating and moving up / downwith an XYZθ-stage. Nickel was deposited at the area where film had been removed by cathodic polarization in the solution beforeremoving the aluminum substrate and anodic oxide films in NaOH solutions. Cylindrical or plain network structures were fabricated successfully.

  8. Defect engineering in Ce-doped aluminum garnet single crystal scintillators

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Kamada, K.; Babin, Vladimir; Pejchal, Jan; Pilařová, K.; Mihóková, Eva; Beitlerová, Alena; Bartosiewicz, Karol; Kurosawa, S.; Yoshikawa, A.

    2014-01-01

    Roč. 14, č. 9 (2014), 4827-4833. ISSN 1528-7483 R&D Projects: GA ČR GA13-09876S; GA MŠk(CZ) LH14266 Institutional support: RVO:68378271 Keywords : scintillators * garnets * luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.891, year: 2014

  9. Garnet photonics toward developing laser diode integrated with optical isolator with Si guiding layer

    Energy Technology Data Exchange (ETDEWEB)

    Yokoi, Hideki; Igarashi, Shun; Uchiumi, Yuki; Tani, Kazuya [Department of Electronic Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan)

    2011-03-15

    A nonreciprocal phase shift occurs in TM modes that travel in magneto-optic waveguides in which magnetization is aligned transverse to the light propagation direction in the film plane. The large nonreciprocal phase shift is obtained when a magneto-optic waveguide comprises a guiding layer with a high-refractive-index material. A magneto-optic waveguide with a Si guiding layer is obtained by depositing the Si layer on a magnetic garnet layer. An optical isolator employing a nonreciprocal phase shift is described which has the magneto-optic waveguide with the Si guiding layer. A laser diode integrated with the optical isolator can be developed by connecting the laser diode on the Si layer in the magneto-optic waveguide, which is a concept of garnet photonics (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Laser arthroscopy of the temporomandibular joint.

    Science.gov (United States)

    Gerard, N; Hendler, B H

    1995-04-01

    Laser surgery is very different than traditional surgery. The clinician must be familiar with the physical properties of the laser to use this instrument safely and properly. Various lasers are available for use in oral and maxillofacial surgery and dentistry, namely the carbon dioxide laser, the neodymium:yttrium-aluminum-garnet laser, and the holmium: yttrium-aluminum-garnet laser (Ho:YAG). Only the Ho:YAG laser has been used with effectiveness in temporomandibular joint arthroscopic surgery. PMID:8935004

  11. “Forbidden” reflections in resonant diffraction of synchrotron radiation in yttrium aluminum garnet Y3Al5O12

    International Nuclear Information System (INIS)

    The purely resonant Bragg reflections (13, 13, 0) and (14, 0, 0) in yttrium aluminum garnet Y3Al5O12 at energies near the K absorption edge of yttrium have been studied experimentally and theoretically. The anisotropic tensor atomic factor of yttrium corresponding to dipole-dipole resonance transitions depends on three independent parameters changing with energy. The intensities of the reflections (14, 0, 0) and (13, 13, 0) are shown to depend on the parameter difference f1(E) − f2(E) and the parameter f3(E), respectively, which are attributable to distortions of the wave functions of the excited atoms and change greatly with photon energy E. Studying various reflections has allowed one to determine the various components of the tensor atomic factor and to compare them with the results of numerical calculations.

  12. Aluminum multicharged ion generation from laser plasma

    International Nuclear Information System (INIS)

    Highlights: • Multicharged Al ions are generated by a ns laser pulse ablation of an Al target in UHV. • Time-of-flight and electrostatic retarding field ion energy analyzers are used to detect the laser-generated MCIs. • For 5 kV accelerating voltage, laser energy of 90 mJ, up to Al+4 with ∼0.65 nC total ion charge is detected. • Raising accelerating voltage increases the charge extraction from the laser plasma and the energy of MCIs. • Ion extraction is dependent on electric field between Al target and extraction mesh. - Abstract: Multicharged aluminum ions are generated by a ns Q-switched Nd:YAG laser pulse ablation of an aluminum target in an ultrahigh vacuum. Time-of-flight and electrostatic retarding field ion energy analyzers are used to detect the laser-generated multicharged ions. The experiments are conducted using laser pulse energies of 45–90 mJ focused on the Al target surface by a lens with an 80-cm focal length to 0.0024 cm2 spot area and incident at 45° with the Al target surface. With the increase in the laser pulse energy, a slow increase in the number of ions generated is observed. The generation of ions with a higher charge state is also observed with the increase in the laser pulse energy. For 5 kV accelerating voltage applied to the Al target and using laser energy of 90 mJ, up to Al+4 with ∼0.65 nC total ion charge is delivered to the detector which is located 140 cm away from the Al target. Raising accelerating voltage increases the charge extraction from the laser plasma and the energy of multicharged ions

  13. Magnetooptics of quintet states of Tb{sup 3+} ion in terbium-yttrium aluminum garnet

    Energy Technology Data Exchange (ETDEWEB)

    Valiev, U.V.; Rustamov, U.R.; Rakhmatov, A.S. [National University of Uzbekistan, 700174 Tashkent (Uzbekistan); Gruber, J.B. [Department of Physics, San Jose State University, San Jose, California 95192-0106 (United States); Zandi, B. [ARL/Adelphi Laboratory Center, 2800 Powder Mill Road, Adelphi, Maryland 20783-1197 (United States); Dzhuraev, D.R.; Narzullaev, N.M. [Bukhara State University, 705018 Bukhara (Uzbekistan)

    2005-03-01

    The luminescence spectra and the degrees of magnetic circular polarization of luminescence (MCPL) have been studied in paramagnetic garnet Tb{sub 0.2}Y{sub 2.8}Al{sub 5}O{sub 12} (YAG:Tb{sup 3+}) for the radiative 4f-4f transition {sup 5}D{sub 4}{yields}{sup 7}F{sub 6}. The features of the spectral dependencies of the MCPL degree with allowed (in symmetry) optical transitions between the Stark sublevels of the ground {sup 7}F{sub 6} and excited {sup 5}D{sub 4} multiplets of the non-Kramers rare-earth Tb{sup 3+} ion have been found in the YAG garnet structure. In the paramagnetic garnet Tb{sub 0.2}Y{sub 2.8}Al{sub 5}O{sub 12} within the close ultraviolet spectral range, the non-trivial features of the spectra of magnetic circular dichroism (MCD) have been found; they evidence a significant contribution of the quasi-doublet states in the multiplets {sup 5}D{sub 3}, {sup 5}G{sub 5} and {sup 5}L{sub 10} to magnetooptics of the 4f-4f transitions. The results of numerical calculations of the energy and wave functions have been presented for some Stark sublevels of the {sup 5}D{sub 4} and {sup 7}F{sub 6} multiplets of the Tb{sup 3+} ion in the crystalline field of D{sub 2} symmetry. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Aluminum alloy nanosecond vs femtosecond laser marking

    Indian Academy of Sciences (India)

    S Rusu; A Buzaianu; D G Galusca; L Ionel; D Ursescu

    2013-11-01

    Based on the lack of consistent literature publications that analyse the effects of laser marking for traceability on various materials, the present paper proposes a study of the influence of such radiation processing on an aluminum alloy, a vastly used material base within several industry fields. For the novelty impact, femtolaser marking has been carried out, besides the standard commercial nanosecond engraving. All the marks have been analysed using profilometry, overhead and cross-section SEM microscopy, respectively and EDAX measurements.

  15. Growth of a multilayer garnet crystal double-clad waveguide structure by pulsed laser deposition

    OpenAIRE

    May-Smith, T.C.; Shepherd, D.P.; EASON, R. W.

    2006-01-01

    We report the growth of a multilayer garnet crystal double-clad waveguide structure by Pulsed Laser Deposition. The structure, grown on a YAG (100) substrate, was fabricated from the sequential deposition of YGG, Nd,Cr:GSGG, YGG and YAG, each layer being about 1 micron in thickness. X-ray diffraction analysis has shown that the layers all grew in the epitaxial (100) orientation and energy dispersive X-ray analysis has revealed that the layer compositions are close to those of the target mater...

  16. Laser perforation of aluminum alloy sheet

    Science.gov (United States)

    Migliore, Leonard; Nazary, George

    2010-02-01

    Recent advances in the design of gain modules for diode-pumped solid-state lasers have allowed the manufacture of high-powered Q-switched products. The high available pulse energy and good mode quality enable highly efficient harmonic conversion, enabling the generation of several hundred watts of average power at a wavelength of 532nm. Among the applications for which this class of product may be suited is the rapid drilling of small-diameter holes in aluminum sheet. To investigate this application, plates of several aluminum alloys were drilled under a variety of conditions. The drilled plates were sectioned and subjected to analysis by optical metallography. The initial results indicate ways in which the process may be optimized.

  17. Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

    Institute of Scientific and Technical Information of China (English)

    Li Huili; Liu Xuejian; Zhang Qitu; Huang Liping

    2007-01-01

    Nanosized cerium-doped lutetium aluminum garnet (LuAG:Ce) phosphors were prepared by nitrate-citrate sol-gel combustion process using 1:1 ratio of the citrate:nitrate. The prepared LuAG:Ce phosphors were characterized by XRD, TEM, photoluminescence and radioluminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG:Ce was obtained at 900 ℃ by directly crystallizing from amorphous materials. The resultant LuAG:Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 nm. Both photoluminescence and radioluminescence were well-known Ce3+ emissions located in the range of 470~600 nm consisting of two emission bands because of the transition from the lowest 5d excited state (2D) to the 4f ground state of Ce3+, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.

  18. Aluminum plasma produced by a nitrogen laser

    International Nuclear Information System (INIS)

    13 mJ laser pulses from a nitrogen laser were focused onto an aluminum target in air. The target surface was perpendicular to the axis of the laser beam. A peak energy density of 1.3 J/cm2 and a power density of 80 MW/cm2 were achieved with a laser pulse duration of 16 ns. This high power density produced a transient plasma cloud that expanded explosively into the surrounding atmosphere. An initial electron density of about 1 x 1019 cm-3 and an electron temperature of about 2 eV were determined by optical spectroscopy. The line of sight was parallel to the surface and perpendicular to the laser beam axis. The height of the line of sight above the target surface was varied in order to gather data about the whole plasma cloud. In about 500 ns the plasma cloud expands to about 0.5 mm above the target surface, cools down to about 1.2 eV and is tenfold reduced in electron density. The initial expansion velocity was determined to be about 2 km/s. (orig.)

  19. In Vitro Evaluation of the Effect of Different Laser Irradiations on the Enamel Surfaces of Teeth Treated with Home Bleach Procedure

    OpenAIRE

    2013-01-01

    Introduction: The aim of this study was to evaluate the effect of dental surface treatment with Erbium-Doped Yttrium Aluminum Garnet(Er: YAG), Neodymium-Doped Yttrium Aluminium Garnet(Nd: YAG) and Carbon Dioxide Laser (CO2) lasers and sodium ascorbate to recently home bleached enamel by scanning electron microscope (SEM).

  20. Phonon spectroscopy of the low-energy excitations in the solid solutions of yttrium–rare-earth metal–aluminum garnets

    International Nuclear Information System (INIS)

    The transport characteristics of thermal-frequency phonons and the specific heat of a series of single crystals of yttrium–rare-earth metal–aluminum garnet solid solutions are studied at the helium temperatures. It is found that the existence of low-energy levels of various origins, which are responsible for an increase in the specific heat, retards phonon transport by one–three orders of magnitude. The temperature dependences of specific heat and the kinetic characteristics of phonons have a similar character

  1. Effect of Hydroquinone Plus Neodymium-Doped Yttrium Aluminium Garnet Laser With and Without CO2 Fractional Laser on Resistant Dermal Melasma

    OpenAIRE

    Zamanian; Behrangi; Ghafarpour; Mehran; Espahbodi; Hoseinzade Fakhim; Azizian

    2015-01-01

    Background The use of different types of lasers in the treatment of refractory melasma is still controversial. The present study was designed according to previous studies and used a combination of treatments. Objectives The purpose of this study was to compare Q-switched (QS) neodymium-doped yttrium aluminium garnet (Nd: YAG) laser and hydroquinone with or without CO2 fractional laser in refractory melasma. ...

  2. Comparison between 0.5% timolol maleate and 0.2% brimonidine tartrate in controlling increase in intraocular pressure after neodymium: yttrium-aluminium-garnet laser capsulotomy

    International Nuclear Information System (INIS)

    Objective: To compare the effectiveness of prophylactically given 0.5% Timolol maleate and 0.2% Brimonidine tartrate in controlling increase in intraocular pressure after neodymium (Nd) : yttrium aluminum garnet (YAG) laser capsulotomy. Study Design: Randomized controlled trial. Place and Duration of Study: This study was conducted at Ophthalmology Department, Jinnah Hospital, Lahore from 15-05-2009 to 14-05-2010 for a duration of 12 months. Material and Methods: In this study, 90 consecutive patients were referred from outpatient department for Nd: YAG laser capsulotomy. Hospital ethical committee's approval for this research proposal and the informed consent was taken. These patients were equally divided into two groups A and B, comprising of 45 patients in each group. Group A was control group which received 0.5% Timolol maleate. Group B was experimental group which received 0.2% Brimonidine tartrate. Intraocular pressure was measured using Goldmann tonometer before instilling these topical medications. These medications were administered topically 1 hour before the laser procedure. Intraocular pressure (IOP) was recorded 1 and 3 hours after laser capsulotomy. Results: In patients belonging to group A, 42 (93.3%) patients had effective control of IOP (raise of less than or equal to 5 mmHg from the baseline) after 3 hours of Nd:YAG laser capsulotomy whereas 28 (62.2%) patients had effective control of IOP after the same period of time in group-B with significant difference (p<0.001). Conclusion: Use of prophylactic topical antiglaucoma medications before doing Nd: YAG laser capsulotomy is a effective way to reduce post laser spike of intraocular pressure. Present study showed that the use of 0.5% timolol maleate was safe and more effective than 0.2% brimonidine tartrate when given 1 hour before laser capsulotomy. (author)

  3. Garnets and perovskites as medium power and single-mode lasers

    International Nuclear Information System (INIS)

    The authors measured laser properties of the new materials Cr, Nd:GSGG; GASG; Cr:GSGG, GSAG; Cr:KZnF/sub 3/ under flashlamp and cw laser excitation. Flashlamp pumping was directly compared to Nd:YAG and alexandrite in different configurations. For single shot operation the efficiency of the double doped material is at least 2-3 times that of Nd:YAG, but decreases for higher mean pump powers. To analyze this behavior they measured the thermal lensing for the different materials by the moire method and obtained for the new garnets, depending on the pumping configuration, up to 7 time stronger lensing than for Nd:YAG at the same pump energies (30-100 J). The main reason for this effect is the broadband absorptions of the chromium ion and of induced color centers in the visible that increase the heat load of the crystal. The heat load and the color center generation can be decreased by effectively blocking the UV light of the flashlamps below 400 nm. For Nd:YAG a 40% output energy saturation effect for pump energies of 120 J was eliminated by dielectric filters resulting in a linear input-output curve. In contrast, a Cr,Nd:GSGG rod still showed a 30% output saturation in spite of blocking

  4. A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm

    Science.gov (United States)

    Liu, J. H.; Han, Y. H.; Zhao, Y. D.

    2013-11-01

    We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2-4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.

  5. Low-relaxation spin waves in laser-molecular-beam epitaxy grown nanosized yttrium iron garnet films

    Science.gov (United States)

    Lutsev, L. V.; Korovin, A. M.; Bursian, V. E.; Gastev, S. V.; Fedorov, V. V.; Suturin, S. M.; Sokolov, N. S.

    2016-05-01

    Synthesis of nanosized yttrium iron garnet (Y3Fe5O12, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10-5. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

  6. Phase stable rare earth garnets

    Science.gov (United States)

    Kuntz, Joshua D.; Cherepy, Nerine J.; Roberts, Jeffery J.; Payne, Stephen A.

    2013-06-11

    A transparent ceramic according to one embodiment includes a rare earth garnet comprising A.sub.hB.sub.iC.sub.jO.sub.12, where h is 3.+-.10%, i is 2.+-.10%, and j is 3.+-.10%. A includes a rare earth element or a mixture of rare earth elements, B includes at least one of aluminum, gallium and scandium, and C includes at least one of aluminum, gallium and scandium, where A is at a dodecahedral site of the garnet, B is at an octahedral site of the garnet, and C is at a tetrahedral site of the garnet. In one embodiment, the rare earth garment has scintillation properties. A radiation detector in one embodiment includes a transparent ceramic as described above and a photo detector optically coupled to the rare earth garnet.

  7. Synthesis and photoluminescence properties of cerium-doped terbium-yttrium aluminum garnet phosphor for white light-emitting diodes applications

    Science.gov (United States)

    Wang, Jun; Han, Tao; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

    2015-11-01

    Cerium-doped terbium-yttrium aluminum garnet phosphors were synthesized using the solid-state reaction method. The crystalline phase, morphology, and photoluminescence properties were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respectively. The XRD results indicate that with an increase of the amount of x (Tb3+), all of the samples have a pure garnet crystal structure without secondary phases. The SEM images reveal that the samples are composed of sphere-like crystallites, which exhibit different degrees of agglomeration. The luminescent properties of Ce ions in )Al5O12∶Ce0.1 have been studied, and it was found that the emission band shifted toward a longer wavelength. The redshift is attributed to the lowering of the 5d energy level centroid of Ce, which can be explained by the nephelauxetic effect and compression effect. These phosphors were coated on blue light-emitting diode (LED) chips to fabricate white light-emitting diodes (WLEDs), and their color-rendering indices, color temperatures, and luminous efficiencies were measured. As a consequence of the addition of Tb, the blue LED pumped )Al5O12∶Ce0.1 phosphors WLEDs showed good optical properties.

  8. Revised calibration of the Sm:SrB4O7 pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale

    International Nuclear Information System (INIS)

    The pressure-induced shift of Sm:SrB4O7 fluorescence was calibrated in a quasi-hydrostatic helium medium up to 60 GPa using the recent Sm-doped yttrium-aluminum garnet primary pressure scale as a reference. The resulting calibration can be written as P = −2836/14.3 [(1 + Δλ/685.51)−14.3 − 1]. Previous calibrations based on the internally inconsistent primary scales are revised, and, after appropriate correction, found to agree with the proposed one. The calibration extended to 120 GPa was also performed using corrected previous data and can be written as P = 4.20 Δλ (1 + 0.020 Δλ)/(1 + 0.036 Δλ)

  9. Energy resolution studies of Ce- and Pr-doped aluminum and multicomponent garnets: the escape and photo-peaks

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Beitlerová, Alena; Průša, Petr; Blažek, K.; Horodysky, P.; Kamada, K.; Yoshikawa, A.; D'Ambrosio, C.; Nikl, Martin

    2016-01-01

    Roč. 169, Jan (2016), s. 701-705. ISSN 0022-2313. [International Conference on Luminescence and Optical Spectroscopy of Condensed Matter /17./. Wroclaw, 13.07.2014-18.07.2014] R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : multicomponent garnets * energy resolution * photo and escape peaks * Ce and Pr dopants * pulse height spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.719, year: 2014

  10. Transurethral laser urethrotomy in man: preliminary report.

    Science.gov (United States)

    Bülow, H; Bülow, U; Frohmüller, H G

    1979-03-01

    After in vitro and in vivo endoscopic laser investigation on normal and experimentally strictured urethras in dogs transurethral laser urethrotomy was done on men. A neodymium: yttrium aluminum garnet laser with a flexible laser light guide was used. The endoscope developed for this purpose is described in detail. The first laser operations were without complications. PMID:430619

  11. Spectroscopic and laser characteristics of Ca, Mg, Zr substituted gadolinium gallium garnet crystals doped with chromium and neodymium

    International Nuclear Information System (INIS)

    Light Raman spectra, spectroscopic and generation charateristics of (Ca, Mg, Zr):(Cr, Nd) crystals of gadolinium-gallium garnet-base (GGG) solid solutions are studied to investigate possibilities of these crystals application as materials for laser active elements. The results presented allow one to expect generation parameters in GGG (Ca, Mg, Zr):(Cr, Nd) crystals, which would be no worse than GSGG-Cr-Nd crystal parameters and a lower temperature of their synthesis (∼ 1700 deg C) may give certain advantages when producing these crystals as compared to more high-temperature IAG and GSGG ones

  12. Laser MBE-grown yttrium iron garnet films on GaN: characterization of the crystal structure and magnetic properties

    Science.gov (United States)

    Kaveev, A. K.; Bursian, V. E.; Gastev, S. V.; Krichevtsov, B. B.; Suturin, S. M.; Volkov, M. P.; Sokolov, N. S.

    2016-07-01

    Yttrium iron garnet (YIG) films were grown on GaN substrates using the laser molecular beam epitaxy method. X-ray diffraction data showed polycrystalline YIG layers without additional structural modifications. The magnetic properties of the YIG films were studied at room temperature with the aid of a vibration sample magnetometer, the magneto-optical Kerr effect and ferromagnetic resonance methods. ‘Easy-plane’-type magnetic anisotropy was found in the films. The gyromagnetic ratio and 4 πMS value were calculated.

  13. Diode-pumped CW and passively Q-switched lasers of Nd:GdLuAG mixed garnet at 1123 nm

    Science.gov (United States)

    Liu, Yang; Liu, Zhaojun; Zhang, Sasa; Xia, Jinbao; Zhang, Yanmin; Guan, Chen

    2016-03-01

    Diode-pumped CW and passively Q-switched lasers of Nd:GdLuAG mixed garnet at 1123 nm were demonstrated. The maximum average output power of CW operation was 4.13 W. For Q-switched operation, the average output power was 800 mW, the corresponding single pulse energy was 133.8 μJ. The Nd:GdLuAG laser emitting at 1123 nm was obtained for the first time to the best of our knowledge, which proves that the Nd:GdLuAG mixed garnet has a better ability of energy storage than Nd:YAG in 1123 nm oscillation.

  14. Time-resolved laser-induced breakdown spectroscopy of aluminum

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-yun; ZHANG Wei-jun; WANG Zhen-ya; HAO Li-qing; HUANG Ming-qiang; ZHAO Wen-wu; LONG Bo; Zhao Wei

    2008-01-01

    We develop a system to measure the elemental composition of unprepared samples using laser-induced breakdown spectroscopy (LIBS) in our laboratory, which can be used for the determination of elements in solids, liquids and aerosols. A description of the instrumentation, including laser, sample chamber and detection, is followed by a brief discussion. The time-resolved LIBS of aluminum at atmospheric pressure is presented. At the end, the possibilities and later uses of this technique are briefly discussed.

  15. Residual stress profiling of an aluminum alloy by laser ultrasonics

    Institute of Scientific and Technical Information of China (English)

    PAN Yondong; QIAN Menglu; XU Weijiang; M. OURAK

    2004-01-01

    A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.

  16. High-pressure optical spectroscopy and X-ray diffraction studies on synthetic cobalt aluminum silicate garnet

    DEFF Research Database (Denmark)

    N. Taran, Michail; Nestola, Fabrizio; Ohashi, Haruo;

    2007-01-01

    The pressure-induced behavior of spin-allowed dd-bands of VIIICo2+ in the absorption spectra of synthetic Co3Al2Si3O12 garnet was studied from 10-4 to 13 GPa. The plots of the peak energy vs. pressure for the three sharpest well resolved bands at ca. 5160, 17 680, and 18 740 cm-1 display small...... but discernible breaks in linear relations between 4 and 5 GPa. Datafromsingle-crystalX-raydiffractionData from single-crystal X-ray diffraction likewise show discontinuities in trends of CoO8 polyhedral volume and distortion, and Co-O and Si-O bond distances over this pressure range. These effects are related...

  17. Computer simulations of laser-induced melting of aluminum

    International Nuclear Information System (INIS)

    Laser-induced solid-to-liquid phase transitions in 100 nm aluminum film were simulated using a hybrid model that combines molecular dynamics (MD) with a continuum description of the laser excitation and a two-temperature method (TTM) to model the relaxation of conduction band electrons. When the laser fluence provides more energy than needed for a complete melting of the film, the phase transition is characterized by an ultrafast collapse of the crystal structure within 2–3 ps. Otherwise, the transition involves a homogeneous nucleation and growth of liquid zones inside the crystal and a heterogeneous propagation of transition fronts from the external surfaces or nucleated liquid zones

  18. Hybrid Laser Would Combine Power With Efficiency

    Science.gov (United States)

    Sipes, Donald L., Jr

    1986-01-01

    Efficient laser system constructed by using two semiconductor lasers to pump neodymium yttrium aluminum garnet (Nd:YAG) device. Hybrid concept allows digital transmission at data rates of several megabits per second with reasonably sized optical aperture of 20 cm. Beams from two GaAs lasers efficiently coupled for pumping Nd:YAG crystal. Combination of lasers exploits best features of each.

  19. 介电谱在镥铝石榴石晶体中的应用%Application of dielectric spectroscopy in lutetium aluminum garnet crystal

    Institute of Scientific and Technical Information of China (English)

    邢琳; 曲良辉; 葛向红; 刘生满; 任海振

    2016-01-01

    为研究提拉法生长的镥铝石榴石单晶中的缺陷,采用波长为254 nm、功率为36 W的4根低压汞灯灯管,室温下在距离镥铝石榴石单晶样品15 cm远处对其进行紫外光辐照24 h,之后在样品上下两个7 mm×7 mm表面镀上电极,置于一夹具内,夹具内部由机械泵维持真空环境,外部由液氮控制温度,利用HP4194A阻抗分析仪对紫外光辐照前后的镥铝石榴石单晶进行介电谱测试。实验结果表明:紫外光辐照后的镥铝石榴石单晶的介电损耗峰出现弛豫,由该弛豫峰对频率的依赖关系表明这种介电弛豫行为是属于偶极子取向极化的弛豫型响应,由此根据偶极子的弛豫机理推断在镥铝石榴石单晶的晶格中可能存在一定数量的缺陷。%To study the defects in lutetium aluminum garnet crystal grown by Czochraski method, samples are irradiated under ultraviolet light (UV) by 4 low pressure mercury lamps (254 nm-wavelength,36 W) placed 15 cm from the samples for 24 h at room temperature. Later,the 7 mmí7 mm surface of these samples is coated with silver films and then placed inside an evacuated cylindrical chamber,the exterior of which is submerged in liquid nitrogen during the experiment. Then, dielectric spectroscopy measurement is performed on both the irradiated and the original samples with a HP4194A impedance analyzer. The results show that the dielectric loss peaks of the irradiated samples appear relaxation effects. The dependency of these relaxation peaks on frequency indicates that the dielectric relaxation behavior is a response to the orientation polarization of a permanent dipole. It therefore can be inferred, according to the relaxation mechanism of the dipole, a certain number of defects may exist in lutetium aluminum garnet crystal.

  20. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, N. S., E-mail: nsokolov@fl.ioffe.ru; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V. [Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Maksimova, K. Yu.; Grunin, A. I. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Tabuchi, M. [Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2016-01-14

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  1. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Science.gov (United States)

    Sokolov, N. S.; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Maksimova, K. Yu.; Grunin, A. I.; Bursian, V. E.; Lutsev, L. V.; Tabuchi, M.

    2016-01-01

    Pulsed laser deposition has been used to grow thin (10-84 nm) epitaxial layers of Yttrium Iron Garnet Y3Fe5O12 (YIG) on (111)-oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  2. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    International Nuclear Information System (INIS)

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y3Fe5O12 (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films

  3. High Power Selective Laser Melting (HP SLM) of Aluminum Parts

    Science.gov (United States)

    Buchbinder, D.; Schleifenbaum, H.; Heidrich, S.; Meiners, W.; Bültmann, J.

    Selective Laser Melting (SLM) is one of the Additive Manufacturing (AM) technologies that enables the production of light weight structured components with series identical mechanical properties without the need for part specific tooling or downstream sintering processes, etc. Especially aluminum is suited for such eco-designed components due to its low weight and superior mechanical and chemical properties. However, SLM's state-of-the-art process and cost efficiency is not yet suited for series-production. In order to improve this efficiency it is indispensable to increase the build rate significantly. Thus, aluminum is qualified for high build rate applications using a new prototype machine tool including a 1 kW laser and a multi-beam system.

  4. Dilution of molybdenum on aluminum during laser surface alloying

    International Nuclear Information System (INIS)

    Highlights: •Laser surface alloying significantly increased the solubility of transition metal. •Laser surface alloying produced dense coating with good metallurgical bonding. •Laser process parameters greatly influenced the evolution of various intermetallics. •Computationally predicted results closely matched with experimental findings. •Ability to generalize present model to other metal-transition metal systems. -- Abstract: A multiphysics based computational model was developed to predict the dilution of molybdenum (Mo) on an aluminum (Al) substrate during the laser surface alloying process. The influence of laser surface alloying processing parameters such as input energy, scanning speed, and overlapping ratio on dilution of Mo in Al was explored via computational model. The computational model, closely predicts the melt pool geometry (width and depth) that subsequently helps in estimating dilution. It was observed that the dilution increases with the increase in laser power, while it decreases with the increase in scanning speed. The phase and microstructural analyses revealed the existence of Al5Mo intermetallic for most of the laser surface alloying processing conditions. However, at higher (3.18 × 107 J/m2) and lower (1.91 × 107 J/m2) laser energy densities, the Al8Mo3 intermetallic was also evolved. These experimental observations validate the model’s predictions and points to its reliability in predicting the expected intermetallics in Al–Mo system for various laser surfacing alloying processing conditions

  5. Highly Efficient Lasing Action of Nd3+- and Cr3+-Doped Yttrium Aluminum Garnet Ceramics Based on Phonon-Assisted Cross-Relaxation Using Solar Light Source

    Science.gov (United States)

    Saiki, Taku; Nakatsuka, Masahiro; Imasaki, Kazuo

    2010-08-01

    We constructed a theory to explain the mechanism of laser generation with a high optical-optical conversion efficiency for Nd3+- and Cr3+-doped yttrium aluminum ceramics when sunlight or lamplight sources are used for pumping. As a result, a unique mechanism of laser action was found where the solar or lamp-light power could be converted to laser power with a high efficiency close to 80%, which has not previously been observed. The high conversion efficiency was not only considered to be based on one-to-one photon conversion but on two-photon excitation by a single photon with phonon assistance. Thus, the mechanism of lasing action should include a process where thermal energy is converted to photon energy. The theoretical results we obtained were consistent with those of the experiments.

  6. High-pressure and high-temperature studies on oxide garnets

    International Nuclear Information System (INIS)

    We report high-pressure and high-temperature studies on a series of oxide garnets of chemical composition A3B2C3O12. The members of this family investigated are gadolinium scandium gallium garnet (GSGG), gadolinium gallium garnet (GGG), and yttrium aluminum garnet (YAG). The GSGG and GGG are doped with both neodymium and chromium while the YAG is doped only with neodymium. Photoluminescence, synchrotron x-ray-diffraction, and laser heating studies were carried out in a diamond-anvil cell. Variety of optical sensors (ruby, Sm-doped YAG) and x-ray pressure marker (copper) were employed for pressure measurement. Pressure-induced amorphization was observed in GSGG at 58±3 GPa and GGG at 84±4 GPa by x-ray-diffraction studies. The photoluminescence studies show only gradual broadening of emission bands through the amorphization transition. On increasing pressure beyond amorphization, very broad and featureless emission bands were observed in the fluorescence spectra at 77±2 GPa for GSGG and at 88±2 GPa for GGG. Laser heating of the pressure-induced amorphous phase in GSGG caused recrystallization to the stable cubic phase. High-pressure x-ray study on YAG shows that it retains cubic phase up to 101±4 GPa. A pressure-volume relation for each member of the oxide garnet at ambient temperatures is presented, structural transformation mechanisms, and application of oxide garnets as pressure sensors are also discussed. copyright 1996 The American Physical Society

  7. High-pressure and high-temperature studies on oxide garnets

    Science.gov (United States)

    Hua, Hong; Mirov, Sergey; Vohra, Yogesh K.

    1996-09-01

    We report high-pressure and high-temperature studies on a series of oxide garnets of chemical composition A3B2C3O12. The members of this family investigated are gadolinium scandium gallium garnet (GSGG), gadolinium gallium garnet (GGG), and yttrium aluminum garnet (YAG). The GSGG and GGG are doped with both neodymium and chromium while the YAG is doped only with neodymium. Photoluminescence, synchrotron x-ray-diffraction, and laser heating studies were carried out in a diamond-anvil cell. Variety of optical sensors (ruby, Sm-doped YAG) and x-ray pressure marker (copper) were employed for pressure measurement. Pressure-induced amorphization was observed in GSGG at 58+/-3 GPa and GGG at 84+/-4 GPa by x-ray-diffraction studies. The photoluminescence studies show only gradual broadening of emission bands through the amorphization transition. On increasing pressure beyond amorphization, very broad and featureless emission bands were observed in the fluorescence spectra at 77+/-2 GPa for GSGG and at 88+/-2 GPa for GGG. Laser heating of the pressure-induced amorphous phase in GSGG caused recrystallization to the stable cubic phase. High-pressure x-ray study on YAG shows that it retains cubic phase up to 101+/-4 GPa. A pressure-volume relation for each member of the oxide garnet at ambient temperatures is presented, structural transformation mechanisms, and application of oxide garnets as pressure sensors are also discussed.

  8. Percutaneous yttrium aluminum garnet-laser lithotripsy of intrahepatic stones and casts after liver transplantation

    DEFF Research Database (Denmark)

    Schlesinger, Nis Hallundbaek; Svenningsen, Peter; Frevert, Susanne;

    2015-01-01

    Bile duct stones and casts (BDSs) contribute importantly to morbidity after liver transplantation (LT). The purpose of this study was to estimate the clinical efficacy, safety, and long-term results of percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) in transplant recipients and to......% needed additional interventions in the form of percutaneous transhepatic cholangiography and dilation (17%), re-PTCSL (11%), self-expandable metallic stents (22%), or hepaticojejunostomy (6%); and 22% eventually underwent retransplantation. The overall liver graft survival rate was 78%. Two patients died...

  9. Supersonic laser-induced jetting of aluminum micro-droplets

    International Nuclear Information System (INIS)

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets

  10. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  11. Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method

    Science.gov (United States)

    Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

    2013-12-01

    A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

  12. Laser and thermal properties of Nd:YGd2Sc2Al2GaO12 garnet ceramic

    International Nuclear Information System (INIS)

    The absorption and fluorescence properties of the Nd-doped YGd2Sc2Al2GaO12 mixed garnet ceramics have been measured at different temperatures. Under laser diode pumping an efficient laser emission has been demonstrated with 45% slope efficiency. The emission is constituted by two lines at 1058.6 and 1061.3 nm, subjected to a red shift and a variable relative intensity versus pump power. The role of the temperature has been investigated playing with the cavity parameters. The thermal conductivity of the 1% Nd-doped material has been determined (3.2 W/m/K) measuring the radial temperature distribution of the exit face of the sample including the axial heat flow in the analysis. The M2 beam quality factor and the dioptric power of the thermal lens have been investigated versus the pump power. The thermo-optic coefficient χ was determined as 44.4×10-6 K-1

  13. Local effects of high-powered neodymium-doped yttrium aluminium garnet laser systems on the pulmonary parenchyma: an experimental study on the isolated perfused pig lung lobe

    OpenAIRE

    Kirschbaum, Andreas; Palade, Emanuel; Kayser, Gian; Passlick, Bernward

    2012-01-01

    Neodymium-doped yttrium aluminium garnet (Nd:YAG) laser systems (with a power output up to 100 W, wavelength 1318 nm) have been introduced into clinical practice for resecting lung metastases. However, the extent of the local effect on the lung parenchyma and the role of the application time are unknown. All experiments were performed on normothermal, whole-blood-perfused paracardiac pig lung lobes (n = 6). Lobes were not ventilated during the laser application. The laser itself was clamped i...

  14. Thermal analysis of intense femtosecond laser ablation of aluminum

    Institute of Scientific and Technical Information of China (English)

    Hu Hao-Feng; Ji Yang; Hu Yang; Ding Xiao-Yan; Liu Xian-Wen; Guo Jing-Hui; Wang Xiao-Lei; Zhai Hong-Chen

    2011-01-01

    This paper numerically simulates the process of ablation of an aluminum target by an intense femtosecond laser with a fluence of 40 J/cm2 based on the two-temperature equation, and obtains the evolution of the free electron temperature and lattice temperature over a large temporal and depth range, for the first time. By investigating the temporal evolution curves of the free electron temperature and lattice temperature at three representative depths of O,100 nm and 500 nm, it reveals different characteristics and mechanisms of the free electron temperature evolution at different depths. The results show that, in the intense femtosecond laser ablation of aluminum, the material ablation is mainly induced by the thermal conduction of free electrons, instead of the direct absorption of the laser energy;in addition, the thermal conduction of free electrons and the coupling effect between electrons and lattice will induce the temperature of free electrons deep inside the target to experience a process from increase to decrease and finally to increase again.

  15. Cracking susceptibility of aluminum alloys during laser welding

    Directory of Open Access Journals (Sweden)

    Lara Abbaschian

    2003-06-01

    Full Text Available The influence of laser parameters in welding aluminum alloys was studied in order to reduce hot cracking. The extension of cracks at the welding surface was used as a cracking susceptibility (CS index. It has been shown that the CS changes with changing welding velocity for binary Al-Cu alloys. In general, the CS index increased until a maximum velocity and then dropped to zero, generating a typical lambda-curve. This curve is due to two different mechanisms: 1 the refinement of porosities with increasing velocity and 2 the changes in the liquid fraction due to decreasing microsegregation with increasing velocities.

  16. Ceramic Laser Materials

    OpenAIRE

    Guillermo Villalobos; Jasbinder Sanghera; Ishwar Aggarwal; Bryan Sadowski; Jesse Frantz; Colin Baker; Brandon Shaw; Woohong Kim

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers,...

  17. Periocular Laser Complications

    OpenAIRE

    Blanco, Gonzalo; Clavero, Antonio; Soparkar, Charles N.S.; Patrinely, James R.

    2007-01-01

    Laser periocular surgery has achieved an increased popularity, particularly since the widespread use of CO2 and erbium:yttrium aluminum garnet laser and more recently with the development of nonablative laser technology. The main target of these techniques is to treat photoaging changes to obtain a rejuvenated skin. Despite the relatively safety of these procedures on experienced hands, postoperative complications affecting the periocular region, and the eye itself, may follow laser surgery. ...

  18. Dynamics of aluminum plasma produced by a nitrogen laser

    International Nuclear Information System (INIS)

    13 mJ laser pulses from a nitrogen laser were focused onto an aluminum target in air. The target surface was perpendicular to the axis of the laser beam. A peak energy density of 1.3 J/cm2 and a power density of 80 MW/cm2 were achieved with a laser pulse duration of 16 ns. The high power density produced a transient plasma cloud that expanded explosively into the surrounding atmosphere. An initial electron density of about 1 x 1019 cm3 and an electron temperature of about 2 eV were determined by optical spectroscopy. The line of sight was parallel to the surface and perpendicular to the laser beam axis. The height of the line of sight above the target surface was varied in order to gather data about the whole plasma cloud. In about 500 ns the plasma cloud expands to about 0.5 mm above the target surface, cools down to about 1.2 eV and is tenfold reduced in electron density. The initial expansion velocity was determined to be about 2 km/s. The experimentally determined plasma parameters were input into numerical models of target heating and plasma expansion. The numerical results outrule the so called outflow model of plasma expansion and show reasonable agreement with an effusion model. The observed discrepancies in observed and calculated plasma parameters are attributed to the fact that the theoretical models describe the plasma expansion in vacuum only. (orig.)

  19. Effect of Hydroquinone Plus Neodymium-Doped Yttrium Aluminium Garnet Laser With and Without CO2 Fractional Laser on Resistant Dermal Melasma

    Directory of Open Access Journals (Sweden)

    Zamanian

    2015-06-01

    Full Text Available Background The use of different types of lasers in the treatment of refractory melasma is still controversial. The present study was designed according to previous studies and used a combination of treatments. Objectives The purpose of this study was to compare Q-switched (QS neodymium-doped yttrium aluminium garnet (Nd: YAG laser and hydroquinone with or without CO2 fractional laser in refractory melasma. Patients and Methods Seventeen patients with refractory melasma, in a split-face randomized trial, received topical hydroquinone and Nd: YAG laser treatment on one half of their face and topical hydroquinone, Nd: YAG laser and CO2 fractional laser on the other half of their face. The patients were then assessed by Melasma area and severity index (MASI over 12 weeks in three treatment sessions with an interval of three to four weeks. Results Seventeen patients with melasma (14 females and three males with mean (± SD age of 38.47 (± 6.29 years (range 29 - 53 were included in this study. The only side effect for the Nd: YAG treatment was erythema observed in two cases (11.8%. The mean MASI scores decreased significantly after six weeks for both therapies. Also, a significant reduction was observed in the mean MASI scores from week six till the end of the study. Controlling for the effect of “MASI score at baseline”, the mean MASI score was significantly lower on the side treated with Nd:YAG + CO2 fractional laser in comparison with the Nd: YAG laser. Conclusions Our study showed that the triple therapy of ND: YAG and ND: YAG + CO2 fractional and hydroquinone cream had high efficiency and low morbidity compared to twofold treatment with ND: YAG and ND: YAG + CO2 fractional.

  20. Laser treatment of aluminum copper alloys: A mechanical enhancement

    International Nuclear Information System (INIS)

    Aluminum-copper alloys are commonly used as structural components for the car and aircraft industry. They combine low density, high strength, high fracture toughness and good machinability. Moreover, the strength and wear-resistance of the surface of alloys are improved by a high power laser beam. In this way the molten surface will be self-quenched by conduction of heat into the bulk. This technique ensures solidification velocities of 0.01--1 m/s. These high solidification velocities have a significant influence on the size and distribution of the morphology. This work concentrates on Al-Cu alloys, in which the Cu content ranges between 0--40 wt.%, and is aimed at describing the mechanical and microstructural properties of these alloys upon variation of the laser scan velocity in the range of 0.0125 to 0.125 m/s

  1. Laser Assisted Joining of Hybrid Polyamide-aluminum Structures

    Science.gov (United States)

    Lamberti, Christian; Solchenbach, Tobias; Plapper, Peter; Possart, Wulff

    The demand for hybrid polymer-metal structures is continuously growing due to their great potential in automotive, aerospace and packaging applications. The expected capabilities are highly diverse and include functional, chemical and mechanical as well as economical and ecological aspects. A novel laser beam joining process for hybrid polyamide-aluminum structures is reported. The spatial and temporal heat input is optimized for optimal bonding quality. At the interface it was proven that the polyamide was not decomposed as a result of excessive thermal stress. It was shown that laser or electro-chemical surface pre-treatment of the aluminum substrate has a distinctive effect on the shear strength of the joint. However, the bond quality does not correspond to a change of surface roughness. Therefore, mechanical interlocking in direct relation to surface topology of the pre-treated substrate is not the principal cause for the bonding phenomenon. Chemical analysis in terms of IR-spectroscopy has shown a physicochemical interaction based on hydrogen bonds.

  2. Directivity measurements in aluminum using a laser ultrasonics system

    International Nuclear Information System (INIS)

    A laser ultrasonics system was setup to measure the directivity (angular dependence pattern) of the amplitude of ultrasonic waves generated in aluminum samples. A pulsed Nd:YAG laser operating at 1064 nm optical wavelength, with typical pulse width (FWHM) of 8 ns, and energy per pulse of 450 mJ, was used to generate the ultrasound waves in the samples. The laser detection system was a Mach-Zehnder interferometer with typical noise-limited resolution of 0.25 nm (rms), frequency range from 50 kHz to 20 MHz, and measurement range from -75 nm/V to +75 nm/V. Two different optical spot sizes of the Nd:YAG laser were used to generate waves in the ablation regime: one was focused and the other was unfocused. Using the obtained data, the directivity graphics were drawn and compared with the theoretical curves, showing a good agreement. The experiments showed the directivity as a function of the optical spot size. For a point ultrasonic source (or focused optical spot), the directivity shows that the longitudinal waves present considerable amplitude in all directions. For a larger ultrasonic source (or an unfocused optical spot) the directivity shows that the longitudinal waves are generated with the higher amplitudes inside angles around ±100.

  3. Directivity measurements in aluminum using a laser ultrasonics system

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, J M S; Pacheco, G M [Instituto Tecnologico de Aeronautica, Praca Marechal Eduardo Gomes, 50 - Vila das Acacias, Sao Jose dos Campos - SP, 12228-900 (Brazil); Tittmann, B R [Pennsylvania State University, 212 Earth and Engr. Sciences Building, University Park - PA, 16802-6812 (United States); Baba, A, E-mail: sakamoto@ieav.cta.br [Hitachi, Ltd., 7-2-1 Omika-cho, Hitachi-shi, Ibaraki-ken, 319-1221 Hitachi (Japan)

    2011-01-01

    A laser ultrasonics system was setup to measure the directivity (angular dependence pattern) of the amplitude of ultrasonic waves generated in aluminum samples. A pulsed Nd:YAG laser operating at 1064 nm optical wavelength, with typical pulse width (FWHM) of 8 ns, and energy per pulse of 450 mJ, was used to generate the ultrasound waves in the samples. The laser detection system was a Mach-Zehnder interferometer with typical noise-limited resolution of 0.25 nm (rms), frequency range from 50 kHz to 20 MHz, and measurement range from -75 nm/V to +75 nm/V. Two different optical spot sizes of the Nd:YAG laser were used to generate waves in the ablation regime: one was focused and the other was unfocused. Using the obtained data, the directivity graphics were drawn and compared with the theoretical curves, showing a good agreement. The experiments showed the directivity as a function of the optical spot size. For a point ultrasonic source (or focused optical spot), the directivity shows that the longitudinal waves present considerable amplitude in all directions. For a larger ultrasonic source (or an unfocused optical spot) the directivity shows that the longitudinal waves are generated with the higher amplitudes inside angles around {+-}10{sup 0}.

  4. Directivity measurements in aluminum using a laser ultrasonics system

    Science.gov (United States)

    Sakamoto, J. M. S.; Tittmann, B. R.; Baba, A.; Pacheco, G. M.

    2011-01-01

    A laser ultrasonics system was setup to measure the directivity (angular dependence pattern) of the amplitude of ultrasonic waves generated in aluminum samples. A pulsed Nd:YAG laser operating at 1064 nm optical wavelength, with typical pulse width (FWHM) of 8 ns, and energy per pulse of 450 mJ, was used to generate the ultrasound waves in the samples. The laser detection system was a Mach-Zehnder interferometer with typical noise-limited resolution of 0.25 nm (rms), frequency range from 50 kHz to 20 MHz, and measurement range from -75 nm/V to +75 nm/V. Two different optical spot sizes of the Nd:YAG laser were used to generate waves in the ablation regime: one was focused and the other was unfocused. Using the obtained data, the directivity graphics were drawn and compared with the theoretical curves, showing a good agreement. The experiments showed the directivity as a function of the optical spot size. For a point ultrasonic source (or focused optical spot), the directivity shows that the longitudinal waves present considerable amplitude in all directions. For a larger ultrasonic source (or an unfocused optical spot) the directivity shows that the longitudinal waves are generated with the higher amplitudes inside angles around ±10°.

  5. Sealing ability of three root-end filling materials prepared using an erbium: Yttrium aluminium garnet laser and endosonic tip evaluated by confocal laser scanning microscopy

    Directory of Open Access Journals (Sweden)

    A Salin Nanjappa

    2015-01-01

    Full Text Available Aims: (1 To compare the sealing ability of mineral trioxide aggregate (MTA, Biodentine, and Chitra-calcium phosphate cement (CPC when used as root-end filling, evaluated under confocal laser scanning microscope using Rhodamine B dye. (2 To evaluate effect of ultrasonic retroprep tip and an erbium:yttrium aluminium garnet (Er:YAG laser on the integrity of three different root-end filling materials. Materials and Methods: The root canals of 80 extracted teeth were instrumented and obturated with gutta-percha. The apical 3 mm of each tooth was resected and 3 mm root-end preparation was made using ultrasonic tip (n = 30 and Er:YAG laser (n = 30. MTA, Biodentine, and Chitra-CPC were used to restore 10 teeth each. The samples were coated with varnish and after drying, they were immersed in Rhodamine B dye for 24 h. The teeth were then rinsed, sectioned longitudinally, and observed under confocal laser scanning microscope. Statistical Analysis Used: Data were analyzed using one-way analysis of variance (ANOVA and a post-hoc Tukey′s test at P < 0.05 (R software version 3.1.0. Results: Comparison of microleakage showed maximum peak value of 0.45 mm for Biodentine, 0.85 mm for MTA, and 1.05 mm for Chitra-CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er:YAG laser when compared with ultrasonics, the difference was found to be statistically significant (P < 0.05. Conclusions: Root-end cavities prepared with Er:YAG laser and restored with Biodentine showed superior sealing ability compared to those prepared with ultrasonics.

  6. Random laser action in stoichiometric Nd3Ga5O12 garnet crystal powder

    Science.gov (United States)

    Iparraguirre, I.; Azkargorta, J.; Kamada, K.; Yoshikawa, A.; Rodríguez-Mendoza, U. R.; Lavín, V.; Barredo-Zuriarrain, M.; Balda, R.; Fernández, J.

    2016-03-01

    This work explores the room temperature infrared random laser (RL) performance of Nd3+ ions in a new stoichiometric Nd3Ga5O12 crystal powder. The time-resolved measurements show that the RL pulse is able to follow the subnanosecond oscillations of the pump pulse profile. The pump threshold energy and the absolute stimulated emission energy have been measured using a method developed by the authors. The laser slope efficiency is the highest compared to other Nd3+ stoichiometric RL crystals.

  7. Mid-Infrared Spectroscopy Analysis of the Effects of Erbium, Chromium:Yattrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) Laser Irradiation on Bone Mineral and Organic Components.

    Science.gov (United States)

    Benetti, Carolina; Ana, Patricia Aparecida; Bachmann, Luciano; Zezell, Denise Maria

    2015-12-01

    The effects of varying the energy density of a high-intensity erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser on the mineral and organic components of bone tissue were evaluated using Fourier transform infrared spectroscopy. Bone samples obtained from the tibias of rabbits were irradiated with five energy densities (3, 6, 8, 12, and 15 J/cm(2)), and the effects on the carbonate to phosphate ratio and in the organic components were compared with those of nonirradiated samples. The increased temperature during the laser irradiation was also measured using infrared thermography to relate the observed spectral changes to the laser thermal effects. The analyses of the infrared spectra suggests that the irradiation with Er,Cr:YSGG promoted changes in bone tissue in both the mineral and organic components that depend on the laser energy density, pointing to the importance of using the proper energy density in clinical procedures. PMID:26555304

  8. Terbium gallium garnet ceramic-based Faraday isolator with compensation of thermally induced depolarization for high-energy pulsed lasers with kilowatt average power

    International Nuclear Information System (INIS)

    A scalable aperture Faraday isolator for high-energy pulsed lasers with kW-level average power was demonstrated using terbium gallium garnet ceramics with water cooling and compensation of thermally induced depolarization in a magnetic field. An isolation ratio of 35 dB (depolarization ratio γ of 3.4 × 10−4) was experimentally observed at a maximum laser power of 740 W. By using this result, we estimated that this isolator maintains an isolation ratio of 30 dB for laser powers of up to 2.7 kW. Our results provide the solution for achieving optical isolation in high-energy (100 J to kJ) laser systems with a repetition rate greater than 10 Hz

  9. Zero ischemia laparoscopic partial thulium laser nephrectomy.

    LENUS (Irish Health Repository)

    Thomas, Arun Z

    2013-11-01

    Laser technology presents a promising alternative to achieve tumor excision and renal hemostasis with or without hilar occlusion, yet its use in partial nephrectomy has not been significantly evaluated. We prospectively evaluated the thulium:yttrium-aluminum-garnet laser in laparoscopic partial nephrectomy (LPN) in our institution over a 1-year period.

  10. Laser-welded Dissimilar Steel-aluminum Seams for Automotive Lightweight Construction

    Science.gov (United States)

    Schimek, M.; Springer, A.; Kaierle, S.; Kracht, D.; Wesling, V.

    By reducing vehicle weight, a significant increase in fuel efficiency and consequently a reduction in CO 2 emissions can be achieved. Currently a high interest in the production of hybrid weld seams between steel and aluminum exists. Previous methods as laser brazing are possible only by using fluxes and additional materials. Laser welding can be used to join steel and aluminum without the use of additives. With a low penetration depth increases in tensile strength can be achieved. Recent results from laser welded overlap seams show that there is no compromise in strength by decreasing penetration depth in the aluminum.

  11. Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium-scandium-gallium garnet

    Science.gov (United States)

    Lupei, V.; Pavel, N.; Lupei, A.

    2014-04-01

    Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4I9/2(2) →4F3/2(1) and 4I9/2(3) →4F3/2(2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment.

  12. Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet

    International Nuclear Information System (INIS)

    Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4I9/2(2) →4F3/2(1) and 4I9/2(3) →4F3/2(2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment. (paper)

  13. Passively Q-switched diode-pumped Yb:YAG laser using Cr 4+-doped garnets

    Science.gov (United States)

    Kalisky, Y.; Labbe, C.; Waichman, K.; Kravchik, L.; Rachum, U.; Deng, P.; Xu, J.; Dong, J.; Chen, W.

    2002-06-01

    We investigate the repetitive modulation in the kHz frequency domain of a passively Q-switched, diode-pumped Yb:YAG laser, by Cr 4+:YAG, Cr 4+:LuAG, and Cr 4+:GSGG saturable absorbers. The results presented here are focused towards the design of a passively Q-switched Yb:YAG microlaser. The free-running performance of both rod and a disk Yb:YAG is characterized and experimental parameters such as gain and loss are evaluated. These values, together with the value of the stimulated emission cross-section, e.g. σem=3.3×10 -20 cm 2 were found to fit between our experimental results and an existing numerical model which relates the experimental and physical parameters to the minimal threshold pumping power. Q-switched pulses with maximum peak power of ≈10.4 kW, with energy of ≈0.5 mJ/pulse, were extracted with 30% extraction efficiency.

  14. Research on the properties of laser welded joints of aluminum killed cold rolled steel

    Institute of Scientific and Technical Information of China (English)

    阎启; 曹能; 俞宁峰

    2002-01-01

    Aluminum killed cold rolled steel used for automobiles was welded shows that high quality of welding can be realized at welding speed of laser welded joints for aluminum killed cold rolled steel increased compared to those of the base metal while the formability decreased. Forming limit diagram of joint material indicated that the laser weld seam should avoid the maximum deformation area of automobile parts during the designing period for the position of weld seam.

  15. Pore formation during C.W.Nd: YAG laser welding of aluminum alloys for automotive applications

    International Nuclear Information System (INIS)

    Pore formation is an important concern in laser welding of automotive aluminum alloys. This paper investigates the influence of the laser beam defocusing on pore formation during continuous wave Nd:YAG laser welding of aluminum automotive alloys 5182 and 5754. It was found that the instability of the keyhole during welding was a dominant cause of pore formation while hydrogen rejection played an insignificant role. The defocusing of the laser beam greatly affected the stability of the keyhole. Finally, the mechanism of the collapse of the keyhole and pore formation is proposed. (Author) 45 refs

  16. Effect of liquid properties on laser ablation of aluminum and titanium alloys

    Science.gov (United States)

    Ouyang, Peixuan; Li, Peijie; Leksina, E. G.; Michurin, S. V.; He, Liangju

    2016-01-01

    In order to study the effect of liquid properties on laser ablation in liquids, aluminum 5A06 and titanium TB5 targets were irradiated by single-pulse infrared laser in isopropanol, distilled water, glycerin and as a comparison, in air, respectively. Craters induced by laser ablation were characterized using scanning electron and white-light interferometric microscopies. The results show that for liquid-mediated ablation, craters with porous surface structures were formed in aluminum target through phase explosion, while no micro-cavities were formed in titanium target owing to high critical temperature of titanium. In addition, ablation rates of aluminum and titanium targets vary with types of ambient media in accordance with such sequence: air isopropanol properties on material-removal mechanisms for laser ablation in liquid is discussed. It is concluded that the density, thermal conductivity and acoustical impedance of liquid play a dominant role in laser ablation efficiency.

  17. Wavelengths effect on mass ablation of laser decontamination on aluminum surface

    International Nuclear Information System (INIS)

    Laser decontamination technology has advantages such as very high decontamination efficiency and very low secondary waste generation even though it has some disadvantages as high initial equipment cost and a little bit slow decontamination speed. Tam et al. reported the laser cleaning techniques for the removal of surface particulates. The existing decontamination methods such as chemical process using an organic solvent or inorganic acid, and a physical method using blasting or brushing generate secondary wastes due to chemicals and abrasives The coolant system of the research reactor in Korea and equipment in hot cells of nuclear facilities are made of aluminum. In the present study, we investigate the effect of wavelength of Q-switched Nd:YAG laser on the removal of Cs, Co, Eu, and Ce on an aluminum surface. Correlation between alumina ablation mass and the laser fluence was evaluated to find the effect of laser fluence on the removal of contaminants on the aluminum surface

  18. Wavelengths effect on mass ablation of laser decontamination on aluminum surface

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sun Hee; Won, Hui Jun; Choi, Byung Seon; Jung, Chong Hun; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Laser decontamination technology has advantages such as very high decontamination efficiency and very low secondary waste generation even though it has some disadvantages as high initial equipment cost and a little bit slow decontamination speed. Tam et al. reported the laser cleaning techniques for the removal of surface particulates. The existing decontamination methods such as chemical process using an organic solvent or inorganic acid, and a physical method using blasting or brushing generate secondary wastes due to chemicals and abrasives The coolant system of the research reactor in Korea and equipment in hot cells of nuclear facilities are made of aluminum. In the present study, we investigate the effect of wavelength of Q-switched Nd:YAG laser on the removal of Cs, Co, Eu, and Ce on an aluminum surface. Correlation between alumina ablation mass and the laser fluence was evaluated to find the effect of laser fluence on the removal of contaminants on the aluminum surface

  19. Femtosecond laser ablation of aluminum in vacuum and air at high laser intensity

    International Nuclear Information System (INIS)

    In this study, the ablation of aluminum by a near-infrared femtosecond laser pulse (800 nm, 100 fs) at different intensity is investigated by a two-dimensional hydrodynamic model. The ablation rates are compared between the cases in vacuum and in air over a wide range of laser power density. It has been reported before that at low (13 W/cm2) and moderate laser intensity (1013–1014 W/cm2), two different ablation regimes exist, and the ablation depth per pulse is dependent on the optical penetration depth and electron heat penetration depth, respectively. By considering both collisional and collisionless absorptions, the model in this study predicts the third ablation regime with a much higher ablation rate increase with respect to laser intensity in the high intensity range (>1014 W/cm2) in vacuum, which shows good agreement with the experimental data. This phenomenon is attributed to the change of dominant absorption mechanism from collisional to collisionless absorption. For the case in air, the ablation depth increases slowly with the laser intensity in the high intensity regime, and is much smaller than that in vacuum. It is revealed that this is due to the strong early plasma-laser interaction in air.

  20. Measurement of pressure changes during laser-activated irrigant by an erbium, chromium: yttrium, scandium, gallium, garnet laser.

    Science.gov (United States)

    Peeters, Harry Huiz; De Moor, Roeland J G

    2015-07-01

    The use of Er,Cr:YSGG laser to activate irrigants results in the creation of vapour bubbles and shockwaves. The present study evaluated the magnitude of pressure changes in the root canal during laser-activated irrigation. The root canal of a single extracted maxillary canine was enlarged to a size 40/0.06 file. A pressure sensor was inserted apically into the root canal. The tooth was processed as follows. In the EDTA condition, the tooth was irrigated with 17 % EDTA; in the NaOCl condition, the tooth was irrigated with 3 % NaOCl. In all conditions, the irrigants were activated at 0.75 and 1.75 W for 60 s using RFT2 and MZ2 tips; to analyse the effect of tip placement, the tip was activated at the orifice and after inserting the tip 5 mm deeper than the orifice. Data showed no significant difference between irrigation regimens (p > 0.05). There were no significant differences of the pressure between RFT2 and MZ2 tips (p > 0.05). The placement of tips closer to the apex resulted in significantly higher pressure than at the orifice (p < 0.001). The use of 1.75 W power resulted in a significantly higher increase of pressure compared to 0.75 W (p < 0.001), regardless either the type of solutions or tips used. The magnitude of the pressure changes in the root canal at 0.75 W was significantly lower than 1.75 W regardless of either type of tips or solutions used. The closer the insertion of the tip to the apex, the higher the pressure. PMID:24906483

  1. High-pressure and high-temperature studies on oxide garnets

    Energy Technology Data Exchange (ETDEWEB)

    Hua, H.; Mirov, S.; Vohra, Y.K. [Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, Alabama 35294-1170 (United States)

    1996-09-01

    We report high-pressure and high-temperature studies on a series of oxide garnets of chemical composition {ital A}{sub 3}{ital B}{sub 2}{ital C}{sub 3}O{sub 12}. The members of this family investigated are gadolinium scandium gallium garnet (GSGG), gadolinium gallium garnet (GGG), and yttrium aluminum garnet (YAG). The GSGG and GGG are doped with both neodymium and chromium while the YAG is doped only with neodymium. Photoluminescence, synchrotron x-ray-diffraction, and laser heating studies were carried out in a diamond-anvil cell. Variety of optical sensors (ruby, Sm-doped YAG) and x-ray pressure marker (copper) were employed for pressure measurement. Pressure-induced amorphization was observed in GSGG at 58{plus_minus}3 GPa and GGG at 84{plus_minus}4 GPa by x-ray-diffraction studies. The photoluminescence studies show only gradual broadening of emission bands through the amorphization transition. On increasing pressure beyond amorphization, very broad and featureless emission bands were observed in the fluorescence spectra at 77{plus_minus}2 GPa for GSGG and at 88{plus_minus}2 GPa for GGG. Laser heating of the pressure-induced amorphous phase in GSGG caused recrystallization to the stable cubic phase. High-pressure x-ray study on YAG shows that it retains cubic phase up to 101{plus_minus}4 GPa. A pressure-volume relation for each member of the oxide garnet at ambient temperatures is presented, structural transformation mechanisms, and application of oxide garnets as pressure sensors are also discussed. {copyright} {ital 1996 The American Physical Society.}

  2. Aluminum film microdeposition at 775 nm by femtosecond laser-induced forward transfer

    Institute of Scientific and Technical Information of China (English)

    Li Yang; Chingyue Wang; Xiaochang Ni; Yinzhong Wu; Wei Jia; Lu Chai

    2007-01-01

    Micro-deposition of an aluminum film of 500-nm thickness on a quartz substrate was demonstrated by laserinduced forward transfer (LIFT) using a femtosecond laser pulse. With the help of atomic force microscopy (AFM) and scanning electron microscopy (SEM), the dependence of the morphology of deposited aluminum film on the irradiated laser pulse energy was investigated. As the laser fluence was slightly above the threshold fluence, the higher pressure of plasma for the thicker film made the free surface of solid phase burst out, which resulted in that not only the solid material was sputtered but also the deposited film in the liquid state was made irregularly.

  3. [Determination of Acid-Insoluble Aluminum Content in Steel by Laser-Induced Breakdown Spectroscopy].

    Science.gov (United States)

    Yang, Chun; Jia, Yun-hai; Zhang, Yong

    2015-03-01

    Laser-induced breakdown spectroscopy (LIBS) has become a very attractive and popular chemical analysis technique in material science for its advantage of rapid analysis, non-contact measurement, micro surface analysis and online analysis. In this paper, LIBS were used to determine insoluble aluminum content by analyzing the scanning data on massive steel samples. Abnormal data were discarded by Nalimov criterion, and the remaining data was used to calculate the average and the standard deviation. The threshold to distinguish acid-insoluble aluminum and soluble aluminum was identified as the average value plus triple standard deviation. Two different mathematical models were proposed to calculate insoluble aluminum content, respectively according to the ratio of the total acid-insoluble aluminium signal strength to total aluminum signal strength and acid-insoluble signal number to total aluminum signal number. The total aluminum content was determined by the calibration curve. Insoluble aluminum content of certified reference materials and plate blank samples obtained by mathematical model is coincident to chemical wet method results. The result according to total acid-insoluble aluminium signal strength is much better. LIBS can be used as a rapid analysis method to characterize insoluble aluminum content in steel samples. PMID:26117896

  4. Simulation of Laser Ablation in Aluminum: The Effectivity of Double Pulses

    OpenAIRE

    Roth, Johannes; Krauß, Armin; Lotze, Jan; Trebin, Hans-Rainer

    2014-01-01

    Lasers are becoming a more and more important tool in cutting and shaping materials. Improving precision and effectivity is an ongoing demand in science and industry. One possibility are double pulses. Here we study laser ablation of aluminum by the two-temperature model. There the laser is modeled as a source in a continuum heat conduction equation for the electrons, whose temperature then is transferred to a molecular dynamics particle model by an electron-phonon coupling term. The melting ...

  5. Study on the Microstructure and Texture of 3003 Aluminum Sheets Rolled by Laser-Textured Roll

    OpenAIRE

    Huajun Zhang; Zesheng Ji; Chunbo Cai; Guojun Wang

    2009-01-01

    In order to improve the surface quality and formability of 3003 aluminum alloy sheet, laser-textured rolls are used in cold rolling. The influences of the cold rolling procedures with conventional and laser-textured rolls on the evolution of microstructure and texture were studied by the means of microstructural observations and X-ray texture analysis. Experimental results show that the microstructures are similar besides the samples rolled with laser-textured rolls containing a relatively la...

  6. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...

  7. Comparing Laser Welding Technologies with Friction Stir Welding for Production of Aluminum Tailor-Welded Blanks

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Carsley, John; Carlson, Blair; Hartfield-Wunsch, Susan; Pilli, Siva Prasad

    2014-01-15

    A comparison of welding techniques was performed to determine the most effective method for producing aluminum tailor-welded blanks for high volume automotive applications. Aluminum sheet was joined with an emphasis on post weld formability, surface quality and weld speed. Comparative results from several laser based welding techniques along with friction stir welding are presented. The results of this study demonstrate a quantitative comparison of weld methodologies in preparing tailor-welded aluminum stampings for high volume production in the automotive industry. Evaluation of nearly a dozen welding variations ultimately led to down selecting a single process based on post-weld quality and performance.

  8. Treatment of Urethral/Bladder Neck Stricture After High-Intensity Focused Ultrasound for Prostate Cancer With Holmium: Yttrium-Aluminium-Garnet Laser

    Science.gov (United States)

    Cho, Won Jin; Kim, Tae Heon; Lee, Hyo Serk; Chung, Jin Woo; Lee, Ha Na

    2013-01-01

    Purpose To evaluate the efficacy and safety of the Holmium: yttrium-aluminium-garnet (YAG) laser for the treatment of urethral/bladder neck strictures after high-intensity focused ultrasound for prostate cancer. Methods Between February 2007 and July 2010, Holmium: YAG laser urethrotomies were performed in eleven patients for bladder neck strictures or prostatic urethral strictures. The laser was used with a 550-µm fiber at 2 J and frequency 30 to 50 Hz. The medical records were retrospectively reviewed for medical history, perioperative and postoperative data, uroflowmetry, International Prostate Symptoms Score/quality of life, and stricture recurrence. Results At a median follow-up of 12.0 months (range, 4 to 35 months), the mean postoperative maximal flow rate and residual volume were improved significantly (Plaser treatment subsequently required artificial urinary sphincter implantation and reported satisfaction without developing any recurrent strictures or artificial urinary sphincter erosion. All patients exhibited well-healed strictures and could void without difficulty. Conclusions Holmium: YAG laser therapy represents a safe, effective and minimally invasive treatment for urethral/bladder neck strictures occurring secondary to high-intensity focused ultrasound for prostate cancer. PMID:23610708

  9. The Adjunctive Use of the Erbium, Chromium: Yttrium Scandium Gallium Garnet Laser in Closed Flap Periodontal Therapy. A Retrospective Cohort Study

    Science.gov (United States)

    Al-Falaki, Rana; Cronshaw, Mark; Parker, Steven

    2016-01-01

    Objectives: The current periodontal literature has been inconsistent in finding an added advantage to using lasers in periodontal therapy. The aim of this study was to compare treatment outcomes following root surface instrumentation alone (NL group), or with adjunctive use of Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser (L group). Material and Methods: Patients diagnosed with generalized chronic periodontitis, having a minimum of 1 year follow up were selected by a blinded party for inclusion in a retrospective analysis from patients treated prior to and after integration of laser in a single clinic setting. Probing depths (PD) of all sites ≥5 mm and full mouth bleeding scores were analyzed. Further analysis was carried out on the treatment outcomes of only the molar teeth and of pockets >6mm. Results: 53 patients were included (25 NL,28 L). There was no significant difference between baseline PDs (NL=6.19mm, L=6.27mm, range 5-11mm). The mean PD after one year was 2.83mm (NL) 2.45mm (L), with the mean PD reductions being 3.35mm (NL) and 3.82mm (L) (pperiodontitis, but the added use of laser may have advantages, particularly in molar tooth sites and deeper pockets. Further research with RCTs is needed to test this hypothesis further. PMID:27350796

  10. Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping

    Science.gov (United States)

    Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

    1991-01-01

    Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

  11. Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system

    Science.gov (United States)

    Fujinaga, Shigeki; Ohashi, Ryoji; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    In high power YAG laser welding of steels, a rectangularly modulated beam with high peak power is usually used to get deep penetration. On the other hand, many spatters and solidification cracks are generated when some aluminum alloys are welded with a rectangularly modulated beam because of its high heat conductivity, high reflectivity, low surface tension, large contraction, wide solidification temperature range, etc. Therefore, a properly modulated beam or a continuous beam is usually used in aluminum alloy welding, although the penetration depth is shallow. In this research, sinusoidal wave or rectangularly modulated wave of YAG laser combined with TIG arc was tried to improve the weldability of A6061 aluminum alloy. As a result, when TIG arc was superimposed behind the YAG laser beam, deeply penetrated weld beads with good surface appearances were produced without spatter losses and cracks.

  12. Numerical simulation of temperature field in deep penetration laser welding of 5A06 aluminum cylinder

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Deep penetration laser welding temperature field of 5A06 aluminum alloy canister structure was simulated using the surface-body combination heat source model by ANSYS, which was made up of Gauss surface heat source model and Gauss revolved body heat source model. Convection, radiation and conduction were all considered during the simulation process. The thermal cycle curves of the points both on the shell outer surface and in the seam thickness direction were calculated. Simulated results agreed well with the experiment results. It concluded that the surface-body combination heat source model was fit for the temperature field simulation of deep penetration laser welding of the aluminum alloy canister structure. This method was proved to be an efficient way to predict the shape and dimension of welded joint for deep penetration laser welding of the aluminum alloy canister structure.

  13. Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications

    Science.gov (United States)

    Verma, Mahesh; Kumari, Pooja; Gupta, Rekha; Gill, Shubhra; Gupta, Ankur

    2015-01-01

    Background: Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique. Materials and Methods: Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3–0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine. Results: The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer. Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength. Conclusions: Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability. PMID:26929482

  14. Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

    Science.gov (United States)

    Jiru, Woldetinsay G.; Sankar, M. Ravi; Dixit, Uday S.

    2016-03-01

    Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

  15. Defect detection in aluminum laser welds using an anisotropic magnetoresistive sensor array

    International Nuclear Information System (INIS)

    For the detection of defects in aluminum laser welds an anisotropic magnetoresistive (AMR) sensor array was implemented in an eddy current testing system. The reliability of weld testing is strongly influenced by the texture of the laser weld whose field response significantly superimposes the defect's magnetic signature. A finite-element model was used to determine the influence of the weld's topology on the detection of defects such as porosities and inclusions hosted in the aluminum matrix. When using an AMR sensor array with field sensitivity of better than 1 nT/√Hz defects with a radius smaller than 100 μm could be detected and classified

  16. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser

    DEFF Research Database (Denmark)

    Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.;

    2010-01-01

    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope eff...

  17. The effect of a pulsed Nd:YAG laser in non-surgical periodontal therapy

    NARCIS (Netherlands)

    D.E. Slot; A.A. Kranendonk; S. Paraskevas; F. van der Weijden

    2009-01-01

    Background: Laser treatment may serve as an alternative or adjunctive treatment to conventional mechanical therapy in periodontics. The neodymium-doped:yttrium, aluminum, and garnet (Nd:YAG) laser has been used in periodontics. Systematic reviews aid in clinical decision-making. The aim of this stud

  18. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser

    DEFF Research Database (Denmark)

    Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.; Zhang, Y.D.; Zhong, X.; Bourdet, G.L.; Wang, J.L.

    2010-01-01

    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...

  19. Enabling lightweight designs by a new laser based approach for joining aluminum to steel

    Science.gov (United States)

    Brockmann, Rüdiger; Kaufmann, Sebastian; Kirchhoff, Marc; Candel-Ruiz, Antonio; Müllerschön, Oliver; Havrilla, David

    2015-03-01

    As sustainability is an essential requirement, lightweight design becomes more and more important, especially for mobility. Reduced weight ensures more efficient vehicles and enables better environmental impact. Besides the design, new materials and material combinations are one major trend to achieve the required weight savings. The use of Carbon Fiber Reinforced Plastics (abbr. CFRP) is widely discussed, but so far high volume applications are rarely to be found. This is mainly due to the fact that parts made of CFRP are much more expensive than conventional parts. Furthermore, the proper technologies for high volume production are not yet ready. Another material with a large potential for lightweight design is aluminum. In comparison to CFRP, aluminum alloys are generally more affordable. As aluminum is a metallic material, production technologies for high volume standard cutting or joining applications are already developed. In addition, bending and deep-drawing can be applied. In automotive engineering, hybrid structures such as combining high-strength steels with lightweight aluminum alloys retain significant weight reduction but also have an advantage over monolithic aluminum - enhanced behavior in case of crash. Therefore, since the use of steel for applications requiring high mechanical properties is unavoidable, methods for joining aluminum with steel parts have to be further developed. Former studies showed that the use of a laser beam can be a possibility to join aluminum to steel parts. In this sense, the laser welding process represents a major challenge, since both materials have different thermal expansion coefficients and properties related to the behavior in corrosive media. Additionally, brittle intermetallic phases are formed during welding. A promising approach to welding aluminum to steel is based on the use of Laser Metal Deposition (abbr. LMD) with deposit materials in the form of powders. Within the present work, the advantages of this

  20. Histological Evaluation of Retina after Photo Disruption for Vitreous Humor by Q-Switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

    Science.gov (United States)

    Kameel Ghaly, Sally; Foad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Medhat Abdel-Salam, Ahmed

    2013-01-01

    Introduction: Rabbits’ eyes were exposed to vitreous humor liquefaction with Q - switched (sometimes called “ giant pulses”) Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser using two different energy protocols (5 mJ X 100 pulse and 10 mJ X 50 pulse)with and without vitamin C administration. The histological changes in the retina were investigated to evaluate the protective role of vitamin C. Methods: The rabbits were divided into four main groups (n= 12 each). The first group was divided into three subgroups (n=4) and then treated with 5 mJ X 100 pulse (X means times) delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group.The third group was divided into three subgroups (n=4) and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed. Results: The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina’s tissues histology after laser. Conclusion: Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina’s layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage. PMID:25606329

  1. A Parametric Analysis of CO2 Laser Heat Absorption Profile of 5083 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available Aluminum alloys are amongst the most difficult everyday metals that can be welded using the laser welding process. For this reason, high power density lasers are needed to weld these alloys because they require higher thermal diffusivity to form a key hole than would be needed for other metals such as steel. This means that more heat wouldhave to be applied while welding aluminum alloys than would be needed to weld steel to achieve a satisfactory coupling effect. The heat input generated from laser welding is affected by the absorptivity coefficient, the welding speed and the time spent. Once the optimum heat input is attained, it is expected to create less heat distortion, its energy is more concentrated within the weld area and deep weld penetration is achieved. Determining optimum values of welding parameters would lead to acceptable weld quality. In this study, the heat absorption profile of a CO2 laser welding of 5083 aluminum alloy was investigated using the models proposed by Bramson in 1968 and Okon et al in 2002. The 4mm thick aluminum alloy investigated was as received from the vendors. The calculated laser beam absorptivity coefficient, irradiance and boiling temperature were 0.12, 2.3 x 106 Wcm-2 and 2482oC respectively. These calculated values compared well with reported values in other literature.

  2. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ming; Chen, Cong; Hu, Ming; Guo, Lianbo; Wang, Zemin, E-mail: zmwang@mail.hust.edu.cn; Zeng, Xiaoyan

    2015-01-30

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view.

  3. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view

  4. Digital laser printing of aluminum micro-structure on thermally sensitive substrates

    Science.gov (United States)

    Zenou, Michael; Sa'ar, Amir; Kotler, Zvi

    2015-05-01

    Aluminum metal is of particular interest for use in printed electronics due to its low cost, high conductivity and low migration rate in electrically driven organic-based devices. However, the high reactivity of Al particles at the nano-scale is a major obstacle in preparing stable inks from this metal. We describe digital printing of aluminum micro-structures by laser-induced forward transfer in a sub-nanosecond pulse regime. We manage to jet highly stable molten aluminum micro-droplets with very low divergence, less than 2 mrad, from 500 nm thin metal donor layers. We analyze the micro-structural properties of the print geometry and their dependence on droplet volume, print gap and spreading. High quality printing of aluminum micro-patterns on plastic and paper is demonstrated.

  5. Digital laser printing of aluminum micro-structure on thermally sensitive substrates

    International Nuclear Information System (INIS)

    Aluminum metal is of particular interest for use in printed electronics due to its low cost, high conductivity and low migration rate in electrically driven organic-based devices. However, the high reactivity of Al particles at the nano-scale is a major obstacle in preparing stable inks from this metal. We describe digital printing of aluminum micro-structures by laser-induced forward transfer in a sub-nanosecond pulse regime. We manage to jet highly stable molten aluminum micro-droplets with very low divergence, less than 2 mrad, from 500 nm thin metal donor layers. We analyze the micro-structural properties of the print geometry and their dependence on droplet volume, print gap and spreading. High quality printing of aluminum micro-patterns on plastic and paper is demonstrated. (paper)

  6. Growth of crystalline garnet mixed films, superlattices and multilayers for optical applications via shuttered combinatorial pulsed laser deposition.

    Science.gov (United States)

    Sloyan, Katherine A; May-Smith, Timothy C; Zervas, Michalis; Eason, Robert W; Huband, Steven; Walker, David; Thomas, Pamela A

    2010-11-22

    A range of crystalline garnet multilayer structures have been fabricated via multi-beam, multi-target PLD in conjunction with a system of mechanical shutters. Structures grown consisted of alternating Gd3Ga5O12 (GGG) and Gd3Sc2Ga3O12 (GSGG) layers on Y3Al5O12 (YAG) substrates, with both simple and chirped designs. Distinct layers are observed where layer thickness is around 2 nm or greater, although some layering may also be present at a sub-unit cell level. These structures demonstrate the viability of the shutter technique as a quick, simple fabrication method for a variety of optical multilayer structures. PMID:21164814

  7. Joint performance of CO2 laser beam welding 5083-H321 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Qi Junfeng; Zhang Dongyun; Xiao Rongshi; Chen Kai; Zuo Tiechuan

    2007-01-01

    Laser beam welding of aluminum alloys is expected to offer good mechanical properties of welded joints. In this experimental work reported, CO2 laser beam autogenous welding and wire feed welding are conducted on 4mm thick 5083-H321 aluminum alloy sheets at different welding variables. The mechanical properties and microstructure characteristics of the welds are evaluated through tensile tests, micro-hardness tests, optical microscopy and scanning electron microscopy (SEM). Experimental results indicate that both the tensile strength and hardness of laser beam welds are affected by the constitution of filler material, except the yield strength. The soften region of laser beam welds is not in the heat-affected zone (HAZ). The tensile fracture of laser beam welded specimens takes place in the weld zone and close to the weld boundary because of different filler materials. Some pores are found on the fracture face, including hydrogen porosities and blow holes, but these pores have no influence on the tensile strength of laser beam welds. Tensile strength values of laser beam welds with filler wire are up to 345.57MPa, 93% of base material values, and yield strengths of laser beam welds are equivalent to those of base metal (264.50MPa).

  8. Effect of adding aluminum ion on the structural, optical, electrical and magnetic properties of terbium doped yttrium iron garnet nanoparticles films prepared by sol–gel method

    International Nuclear Information System (INIS)

    Highlights: • The conductivity of YIG films increased with increasing of Al content. • The saturation magnetization at room temperature decreased with increasing Al3+ content. • Al3+ substituted Tb-YIG films has been prepared by a sol-gel method. - Abstract: Tb0.8Y2.2AlyFe5−yO12 nanoparticle films with y = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by a sol–gel method for potential use as a magnetic sensor and in magneto-optical applications. The films were deposited onto quartz substrate, followed by annealing at 900 °C in air for 2 h. X-ray diffractometry results confirmed the formation of a pure garnet structure. The lattice parameter decreased with increasing Al3+ content due to the substitution of Al3+ ions with the larger Fe3+ ions. The grain size of the films decreased up to y = 0.6. This variation is discussed based on the stress on the grain surface. The films observed to be transparent between 76 and 92% in the visible and infrared regions. The films demonstrated a strong absorption of 104 cm−1 caused by the charge transfer transition in the UV region. The absorption edge shifts to lower wavelengths at higher Al contents of 0.8 and 1 due to electronic transitions. The conductivity of films increased with increasing of Al content due to the increasing in free carrier concentration. The saturation magnetization at room temperature decreased with increasing Al3+ content, whereas the coercivity increased markedly at y = 0.6

  9. Foam coating on aluminum alloy with laser cladding

    NARCIS (Netherlands)

    Ocelik, V.; van Heeswijk, V.; de Hosson, J.T.M.; Csach, K.

    2004-01-01

    dThis article concentrates on the creation of a foam layer on an Al-Si substrate with laser technology. The cladding of At-Si powder in the front of a laser track has been separated from the side injection of mixture of Al-Si/TiH2 powder (foaming agent), which allows for fine tuning of the main proc

  10. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    Science.gov (United States)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-05-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  11. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    Science.gov (United States)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  12. Drilling of aluminum and copper films with femtosecond double-pulse laser

    Science.gov (United States)

    Wang, Qinxin; Luo, Sizuo; Chen, Zhou; Qi, Hongxia; Deng, Jiannan; Hu, Zhan

    2016-06-01

    Aluminum and copper films are drilled with femtosecond double-pulse laser. The double-pulse delay is scanned from -75 ps to 90 ps. The drilling process is monitored by recording the light transmitted through the sample, and the morphology of the drilled holes is analyzed by optical microscopy. It is found that, the breakthrough time, the hole evolution during drilling, the redeposited material, the diameters of the redeposited area and the hole, change as functions of double-pulse delay, and are different for the two metals. Along the double-pulse delay axis, three different time constants are observed, a slow one of a few tens of picoseconds, a fast one of a few picoseconds, and an oscillation pattern. Results are discussed based on the mechanisms of plasma shielding, electron-phonon coupling, strong coupling of laser with liquid phase, oxidation of aluminum, laser induced temperature and pressure oscillations, and the atomization of plume particles.

  13. Ablation characteristics of aluminum oxide and nitride ceramics during femtosecond laser micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Hoon [School of Information and Mechatronics, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong Buk-gu, Gwangju 500-712 (Korea, Republic of); Sohn, Ik-Bu [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong Buk-gu, Gwangju 500-712 (Korea, Republic of); Jeong, Sungho, E-mail: shjeong@gist.ac.kr [School of Information and Mechatronics, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2009-09-30

    Femtosecond laser ablation of aluminum oxide (Al{sub 2}O{sub 3}) and aluminum nitride (AlN) ceramics was performed under normal atmospheric conditions ({lambda} = 785 nm, {tau}{sub p} = 185 fs, repetition rate = 1 kHz), and threshold laser fluencies for single- and multi-pulse ablation were determined. The ablation characteristics of the two ceramics showed similar trends except for surface morphologies, which revealed virtually no melting in Al{sub 2}O{sub 3} but clear evidence of melting for AlN. Based on subsequent X-ray photoelectron spectroscopy (XPS) analyses, the chemistry of these ceramics appeared to remain the same before and after femtosecond laser ablation.

  14. Comparison of the effect of hand instruments, an ultrasonic scaler, and an erbium-doped yttrium aluminium garnet laser on root surface roughness of teeth with periodontitis: a profilometer study

    OpenAIRE

    Amid, Reza; Kadkhodazadeh, Mahdi; Fekrazad, Reza; Hajizadeh, Farzin; Ghafoori, Arash

    2013-01-01

    Purpose The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation. Methods Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acr...

  15. Laser-Ultrasonic Measurement of Elastic Properties of Anodized Aluminum Coatings

    Science.gov (United States)

    Singer, F.

    Anodized aluminum oxide plays a great role in many industrial applications, e.g. in order to achieve greater wear resistance. Since the hardness of the anodized films strongly depends on its processing parameters, it is important to characterize the influence of the processing parameters on the film properties. In this work the elastic material parameters of anodized aluminum were investigated using a laser-based ultrasound system. The anodized films were characterized analyzing the dispersion of Rayleigh waves with a one-layer model. It was shown that anodizing time and temperature strongly influence Rayleigh wave propagation.

  16. K-Shell Spectra from CH-Tamped Aluminum Layers Irradiated with Intense Femtosecond Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    XIONG Gang; ZHAO Yang; SHANG Wan-Li; HU Zhi-Min; ZHU Tuo; WEI Min-Xi; YANG Guo-Hong; ZHANG Ji-Yan; YANG Jia-Min

    2010-01-01

    @@ X-ray spectra of H-like and He-like aluminum ions from aluminum buried in CH layers irradiated with 3Ofs,200 TW laser are measured.The electron temperature and density are derived from line ratios of the He-αresonance line to its satellite lines.Typical temperatures 0f 490-646 eV and electron densities up to 7 × 1020 cm-3are obtained.The results show that the electron density increases and temperature decreases with the increasing CH thickness.

  17. Laser alloyed Al-W coatings on aluminum for enhanced corrosion resistance

    International Nuclear Information System (INIS)

    Highlights: • Al4W intermetallic phase was formed after laser surface alloying. • Potential–time measurements show the stable behavior after laser surface alloying. • Cyclic polarization indicates increase in corrosion resistance after laser surface alloying. - Abstract: A tungsten precursor deposit was spray coated on aluminum 1100 substrate and was subsequently surface alloyed using a continuous wave diode-pumped ytterbium laser at varying laser energy densities. For the laser energy input of 21–32 J/mm2 the melt depth ranged between 135 and 150 μm. Scanning electron microscopy observations indicated the formation of uniform and continuously dense laser alloyed coatings with sound interface between the modified surface and substrate along with an equi-axed grain structure with second phase precipitates in the intergranular region. X-ray diffraction analysis confirmed that laser processing has resulted in the formation of Al4W, as the major phase with retention of W in Al within the alloyed region. The corrosion resistance of laser alloyed coatings was evaluated in near natural chloride solution using ac and dc electrochemical techniques. After laser processing potential–time measurements has indicated the relatively stable and high potential values over the longer exposure times. Cyclic polarization results showed the reduction in the corrosion current density by a factor of 8, compared to untreated Al 1100. Besides, the electrochemical impedance spectroscopy confirmed the increase in the total resistance (47–70 kΩ cm2) with the increase in the laser energy density

  18. Laser-direct-driven quasi-isentropic experiments on aluminum

    International Nuclear Information System (INIS)

    Laser-direct-driven ramp compression experiments were performed on long temporally shaped laser pulses based on an analytical isentropic compression model. Upper pressure limits, the ablation pressure scaling law, and stress-density curves were studied. The validity of the analytical model used, the ablation pressure scaling law, and the phenomena of missing line-imaging velocity interferometer (VISAR) fringes in the experimental results are discussed

  19. One-step fabrication of near superhydrophobic aluminum surface by nanosecond laser ablation

    Science.gov (United States)

    Jagdheesh, R.; García-Ballesteros, J. J.; Ocaña, J. L.

    2016-06-01

    Inspired by the micro and nano structures of biological surface such as lotus leaf, rice leaves, etc. a functional near superhydrophobic surface of pure aluminum has been fabricated using one-step nanosecond laser processing. Thin aluminum sheets are micro-patterned with ultraviolet laser pulses to create near superhydrophobic surface in one-step direct laser writing technique. The impact of number of pulses/microhole with respect to the geometry and static contact angle measurements has been investigated. The microstructure shows the formation of blind microholes along with the micro-wall by laser processing, which improves the composite interface between the three phases such as water, air and solid, thus enhance the wetting property of the surface. The geometrical changes are supported by the chemical changes induced on the surface for improving the degree of hydrophobicity. Laser processed microholes exhibited near superhydrophobic surface with SCA measurement of 148 ± 3°. The static contact angle values are very consistent for repeated measurement at same area and across the laser patterned surface.

  20. Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment

    Energy Technology Data Exchange (ETDEWEB)

    Saad, Rawad, E-mail: rawad.saad@cea.fr [CEA, DEN, DPC, SEARS, LANIE, 91191 Gif-sur-Yvette (France); L' Hermite, Daniel, E-mail: daniel.lhermite@cea.fr [CEA, DEN, DPC, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Bousquet, Bruno, E-mail: bruno.bousquet@u-bordeaux1.fr [LOMA, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33405 Talence Cedex (France)

    2014-11-01

    The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 μs after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals. - Highlights: • Persistence of two Al I lines related to the 61,844 cm{sup −1} energy level only under nitrogen atmosphere. • Collisional energy transfer effect exists between aluminum and nitrogen. • Observation of molecular band of AlN (under nitrogen) and AlO (under air) after a delay time of 1.5 µs. • 20% of oxygen in air is sufficient to annihilate both the collisional energy transfer effect and the AlN molecular formation.

  1. Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment

    International Nuclear Information System (INIS)

    The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 μs after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals. - Highlights: • Persistence of two Al I lines related to the 61,844 cm−1 energy level only under nitrogen atmosphere. • Collisional energy transfer effect exists between aluminum and nitrogen. • Observation of molecular band of AlN (under nitrogen) and AlO (under air) after a delay time of 1.5 µs. • 20% of oxygen in air is sufficient to annihilate both the collisional energy transfer effect and the AlN molecular formation

  2. Laser mass spectrometric detection of AlH molecules as collision-free excimer laser photoproducts from aluminum alkyls

    Science.gov (United States)

    Zhang, Y.; Stuke, M.

    1988-08-01

    Aluminum hydride molecules AlH are detected and identified by tunable dye-laser mass spectroscopy as collision-free UV excimer laser photoproducts of the Al alkyls TEA (triethylaluminum (C 2H 5) 3Al) and TIBA (triisobutylaluminum ( i-C 4H 9) 3Al) at 248 and 193 nm. An internal energy distribution analysis of the photoproducts shows only minor vibrational excitation of ν″ = 1 and a Boltzmann-type rotational energy distribution with a temperature of about 0.03 eV, compared to the incoming photon energy of 5.0 or 6.42 eV.

  3. Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis.

    Science.gov (United States)

    Silva, M Z; Gouyon, R; Lepoutre, F

    2003-06-01

    Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The out of plane surface displacements produced by the propagating ultrasonic waves were detected with a heterodyne Mach-Zehnder interferometer. Time-frequency analysis of the signals using a continuous wavelet transform allowed the identification of the generated Lamb modes by comparison with the calculated dispersion curves. The presence of back surface corrosion was detected by noting the loss of the S(1) mode near its cutoff frequency. This method is applicable to fast scanning inspection techniques and it is particularly suited for early corrosion detection. PMID:12782263

  4. Monitoring of solidification crack propagation mechanism in pulsed laser welding of 6082 aluminum

    Science.gov (United States)

    von Witzendorff, P.; Kaierle, S.; Suttmann, O.; Overmeyer, L.

    2016-03-01

    Pulsed laser sources with pulse durations in the millisecond regime can be used for spot welding and seam welding of aluminum. Seam welds are generally produced with several overlapping spot welds. Hot cracking has its origin in the solidification process of individual spot welds which determines the cracking morphology along the seam welding. This study used a monitoring unit to capture the crack geometry within individual spot welds during seam welding to investigate the conditions for initiation, propagation and healing (re-melting) of solidification cracking within overlapping pulsed laser welds. The results suggest that small crack radii and high crack angles with respect to welding direction are favorable conditions for crack healing which leads to crack-free seam welds. Optimized pulse shapes were used to produce butt welds of 0.5 mm thick 6082 aluminum alloys. Tensile tests were performed to investigate the mechanical strength in the as-welded condition.

  5. Analysis of time phase of characteristic rad iation in plasma induced by laser ablating aluminum

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With time- and space-resolved technique, we have recorde d time-resolved spectra of irradiation of the plasma induced by Nd: YAG laser a blating metal Aluminum in Ar, in which, laser pulse-energy was set up to 145 mJ /pulse and the buffer pressure 100 kpa. The continuum radiation and special emis sion of Aluminum plasma were studied based on the records. According to time dis tribution of Al Ⅰ396.15 nm emission, we analyzed the time differences between c haracteristic and continuum radiation evolving. We tried to explain the time pha ses of characteristic radiation evolving with traditional theoretical model of a tomic transition. As the result, we found that it was difficult to explain our e xperimental results with the model. In order to explain our experimental results , we need new model or to improve the traditional theoretical model of atomic tr ansition.

  6. Characterization of microstructures induced in the workpiece of aluminum alloy by excimer laser micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ye [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Li, Irene Ling, E-mail: liling@szu.edu.cn [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Fu Ling; Zhai Jianpang; Ruan Shuangchen [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China)

    2009-09-15

    Excimer laser emitting at 248 nm is applied to produce microstructures on the surface of aluminum alloy. The surface morphology shows that hotspots and thermal fluidic structures both come to light. Two possible mechanisms of hotspots formation are proposed: near-field diffraction and interference, and extremely fast rapid thermal annealing. And for the formation of thermal fluidic pattern structure, a thin film model is applied.

  7. Application of slip-band visualization technique to tensile analysis of laser-welded aluminum alloy

    OpenAIRE

    Muchiar, Ir.; Yoshida, S.; Widiastuti, R.; Kusnovo, A.; Takahashi, K; Sato, S.

    1996-01-01

    Recently we have developed a new optical interferometric technique capable of visualizing slip band occurring in a deforming solid-state object. In this work we applied this technique to a tensile analysis of laser-welded aluminum plate samples, and successfully revealed stress concentration that shows strong relationships with the tensile strength and the fracture mechanism. We believe that this method is a new, convenient way to analyze the deformation characteristics of welded objects and ...

  8. Molecular dynamics simulations of cluster distribution from femtosecond laser ablation in aluminum

    Science.gov (United States)

    Sonntag, S.; Trichet Paredes, C.; Roth, J.; Trebin, H.-R.

    2011-08-01

    Femtosecond laser ablation and plume evolution of aluminum is investigated for various inhomogeneous laser pulses. For the simulations of the atoms the molecular dynamics code IMD is used. The ablated gas-phase is scanned by a cluster algorithm (DBSCAN), from which we gain a cluster size distribution of the ablated material. Per single pulse, only a small portion of the total volume evaporates into the gas phase. Therefore—to have reasonable statistics—we have to deal with huge samples (6×107 atoms). The ablation threshold is determined by comparing the depth of the holes to the applied fluence. Angular and velocity distributions of the plume are compared to experiments.

  9. Exploration of the fragmentation of laser shock-melted aluminum using x-ray backlighting

    Directory of Open Access Journals (Sweden)

    Lin Zhang

    2016-05-01

    Full Text Available The fragmentation of shock-melted metal material is an important scientific problem in shock physics and is suitable for experimentally investigating by the laser-driven x-ray backlighting technique. This letter reports on the exploration of laser shock-melted aluminum fragmentation by means of x-ray backlighting at the SGII high energy facility in China. High-quality and high-resolution radiographs with negligible motion blur were obtained and these images enabled analysis of the mass distribution of the fragmentation product.

  10. Exploration of the fragmentation of laser shock-melted aluminum using x-ray backlighting

    Science.gov (United States)

    Zhang, Lin; Li, Ying-Hua; Li, Xue-Mei; Ye, Xiang-Ping; Zhang, Zu-Gen; Cheng, Jin-Ming; Cai, Ling-Cang

    2016-05-01

    The fragmentation of shock-melted metal material is an important scientific problem in shock physics and is suitable for experimentally investigating by the laser-driven x-ray backlighting technique. This letter reports on the exploration of laser shock-melted aluminum fragmentation by means of x-ray backlighting at the SGII high energy facility in China. High-quality and high-resolution radiographs with negligible motion blur were obtained and these images enabled analysis of the mass distribution of the fragmentation product.

  11. Laser Shock Peening of Aluminum Alloy 7050 for Fatigue Life Improvement

    Institute of Scientific and Technical Information of China (English)

    Qian; Ming; Lian; Ying; Zou; Shikun; Gong; Shuili

    2007-01-01

    The effects of laser shock peening (LSP) on improving fatigue life of aluminum alloy 7050 are investigated.Surface hardness is increased corresponding to a high dislocation density induced by LSP.The X-ray diffraction stress measurement shows that LSP results in prominent increase of surface compressive stress,quasi-symmetrically distributed in the laser peened region.The fatigue life of the alloy 7050 in rivet fastener hole structure is notably improved owing to LSP.The sequence of LSP and fastener hole preparation also influence the fatigue cycle life of the alloy.

  12. Spaced-Resolved Electron Density of Aluminum Plasma Produced by Frequency-Tripled Laser

    Institute of Scientific and Technical Information of China (English)

    Yang Boqian; Han Shensheng; Zhang Jiyan; Zheng Zhijian; Yang Guohong; Yang Jiaming; Li Jun; Wang Yan

    2005-01-01

    By using the space-resolved spectrograph, the K-shell emission from laser-produced plasma was investigated. Electron density profiles along the normal direction of the target surface in aluminum laser-plasmas were obtained by two different diagnostic methods and compared with the profiles from the theoretical simulation of hydrodynamics code MULTI1D. The results corroborate the feasibility to obtain the electron density above the critical surface by the diagnostic method based on the Stark-broadened wings in the intermediately coupled plasmas.

  13. Optimization of the super lateral energy in laser surface alloying of aluminum

    International Nuclear Information System (INIS)

    An aluminum substrate has been alloyed with an iron and copper mixture by a laser induced plasma technique. The nanosecond pulse duration and the high plasma temperature expose the interacting materials to decalescent and recalescent regions, contributing to the formation of new chemical composites such as AlFeCu, AlFe, AlCu and CuFe. The microstructure of the alloyed surface is observed to be heterogeneous, with no crack formation and with few pores. The hardness of the laser treated surface is 103 HV, seven times harder than that of the substrate (15 HV) at a corresponding super lateral energy of 5282 mJ cm−2. (letter)

  14. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments

    OpenAIRE

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-01-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser t...

  15. Elimination of Lubricants from Aluminum Cold Rolled Products Using Short Laser Pulses

    Directory of Open Access Journals (Sweden)

    Lima M.S.F.

    2002-01-01

    Full Text Available This work presents a new technique to remove the surface impurities from the aluminum cold-worked sheets. The method consists to concentrate a short-time high-power pulsed laser on the materials surface and scan it in order to cover a desired area. Incrustations ablation is obtained as long as the fluency and the peak power are high enough to produce vaporization of the contaminated layer without affecting the material surface properties. The present problem consists in eliminating a desiccated soap of about 1 g/m² from the surface of a 6016-class aluminum alloy sheet. The soap is originated from the rolling process. The present laser method is intended to replace water washing when the piece cannot be soaked, when drying is difficult due to the geometry, or when environmental restrictions apply. Best results were obtained when the pulse length was 100 ns and the average laser power was 95 W. In these conditions, the surface was completely cleaned and the aluminum alloy did not suffer any structural modification.

  16. Investigation of the local thermodynamic equilibrium of laser-induced aluminum plasma by Thomson scattering technique

    International Nuclear Information System (INIS)

    A laser Thomson scattering method was applied to investigate the local Saha–Boltzmann equilibrium in aluminum laser-induced plasma. Plasma was created in ambient air using 4.5 ns pulses from a Nd:YAG laser at 532 nm, focused on an Al target. Spatially resolved measurements, performed for the time interval between 600 ns and 3 μs, show electron density and temperature to decrease from 3.4 × 1023 m−3 to 0.5 × 1023 m−3 and from 61,000 K to 13,000 K in the plasma core. The existence of local thermodynamic equilibria in the plasma was verified by comparing the rates of the collisional to radiative processes (the McWhirter criterion), as well as relaxation times and diffusion lengths of different plasma species, with the appropriate rate of electron density evolution and its gradients at given, experimentally determined, electron temperatures. We found these criteria to be much easier to satisfy for metallic plasma species than for nitrogen. The criteria are also easier to satisfy in the plasma core of higher electron density. - Highlights: • Laser Thomson scattering method was applied to investigate aluminum laser-induced plasma. • Spatio-temporal evolution of electron temperature and density was determined. • Three criteria for existence of local thermodynamic equilibrium were verified. • Criteria are much easier to satisfy for metallic plasma species than for nitrogen. • Criteria are easier to satisfy at earlier times and in the plasma core

  17. Experimental investigation of laser beam welding of explosion-welded steel/aluminum structural transition joints

    International Nuclear Information System (INIS)

    The steel/aluminum structural transition joints are widely used in shipbuilding industry due to the advantages of joining these two materials with important weight savings while exploiting their best properties. The use of laser welding to strongly connect components made of Fe and Al alloys as base materials with Fe/Al structural transition joints is very attractive. The authors report results achieved during the laser welding of these particular joints with the scope to evaluate effects of the laser-induced thermal loads on the integrity of the Fe/Al bond interface, from metallurgical and mechanical points of view. The increase of both inter-metallic film thickness and extension were detected as a result of the laser beam induced heat on the Fe/Al bond interface. These increases did not cause severe reductions of the mechanical resistance of the investigated structural transition joint.

  18. Controlling energy coupling and particle ejection from aluminum surfaces irradiated with ultrashort laser pulses

    International Nuclear Information System (INIS)

    Hydrodynamic simulations are used to evaluate the potential of ultrashort laser pulses to localize energy at metallic surfaces, in our case aluminum. The emphasis is put on the dynamic sequence of laser energy deposition steps during the electron-ion nonequilibrium stage and the subsequent matter transformation phases. The simulations indicate correlated optical and thermodynamical states associated to specific electronic collisional mechanisms. The timescales of energy deposition deliver a guideline for using relevant relaxation times to improve the energy coupling into the material. We focus on a class of pump-probe experiments which investigate energy storage and particle emission from solids under ultrafast laser irradiation. Moreover, we have used our model to explain the experimentally observed optimization of energy coupling by tailoring temporal laser intensity envelopes and its subsequent influence on the ablation rate and on the composition of ablation products. Potential control for nanoparticle generation is discussed.

  19. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    Science.gov (United States)

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin

    2016-08-01

    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  20. The reaction of yttrium-aluminium garnet with t-zirconia

    International Nuclear Information System (INIS)

    The reaction of 6 mol% Y2O3 stabilized tetragonal zirconia (t-ZrO2) with yttrium-aluminum garnet (Y3Al5O12, YAG) was studied at temperatures between 1200 degrees C and 1625 degrees C. Reaction couples were made from polished 0.2 μm grain size plates of hot-pressed Tosoh TZ-3Y t-ZrO2 with 6 mol% yttria. Some plates were not pressed under vacuum in carbon dies with YAG powder prepared from yttrium and aluminum alkoxides. Other plates were coated with a metal alkoxide derived YAG sol or coated by laser vapor deposition of YAG, and then heat-treated in air in a Netzsch thermogravimetric furnace. The reaction products and microstructures are characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy with energy dispersive spectrometry

  1. Laser surface treatment of aluminum based composite mixed with B4C particles

    Science.gov (United States)

    Yilbas, B. S.; Karatas, C.; Karakoc, Halil; Abdul Aleem, B. J.; Khan, S.; Al-Aqeeli, N.

    2015-03-01

    Laser treatment of hot pressed mixture of aluminum (85 wt%) and B4C (15 wt%) is carried out. Metallurgical and morphological changes at the laser treated surface are examined using the analytical tools. Microhardness and fracture toughness of the workpiece surfaces are determined prior to and after the laser treatment process. Texture and hydrophobicity of the laser treated surface is assessed incorporating the atomic force microscopy and contact angle measurements. It is found that a dense layer consisting of fine grains of sub-micron sizes (0.8-0.4 μm) and B4C particles is formed at the laser treated surface. Microhardness increases at the laser treated surface because of the presence of the dense layer and the formation of AlN compounds at the surface. Fracture toughness of the laser treated surface reduces slightly because of the microhardness enhancement at the surface. The textures of the laser treated surface compose of micro/nano poles, which result in higher contact angles than that of the untreated surface, and formation of AlN compound adds to the surface hydrophobicity enhancements.

  2. Ultrafast laser induced periodic sub-wavelength aluminum surface structures and nanoparticles in air and liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kuladeep, Rajamudili; Dar, Mudasir H.; Rao, D. Narayana, E-mail: dnrsp@uohyd.ac.in, E-mail: dnr-laserlab@yahoo.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Deepak, K. L. N. [Department of Physics and Center for Research in Photonics, University of Ottawa, 150 Louis Pasteur, Ottawa K1N6N5, Ontario (Canada)

    2014-09-21

    In this communication, we demonstrate the generation of laser-induced periodic sub-wavelength surface structures (LIPSS) or ripples on a bulk aluminum (Al) and Al nanoparticles (NPs) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Al surface at normal incidence in air and by immersing in ethanol (C₂H₅OH) and water (H₂O) using linearly polarized Ti:sapphire fs laser pulses of ~110 fs pulse duration and ~800 nm wavelength. Field emission scanning electron microscope is utilized for imaging surface morphology of laser written structures and it reveals that the spatial periodicity as well as the surface morphology of the LIPSS depends on the surrounding dielectric medium and also on the various laser irradiation parameters. The observed LIPSS have been classified as low spatial frequency LIPSS which are perpendicularly oriented to the laser polarization with a periodicity from 460 to 620 nm and high spatial frequency LIPSS which spectacles a periodicity less than 100 nm with the orientation parallel to the polarization of the incident laser beam. Fabricated colloidal solutions, which contain the Al NPs, were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). TEM results reveal the formation of internal cavities in Al NPs both in ethanol and water. Formation mechanism of LIPSS and cavities inside the nanoparticles are discussed in detail.

  3. Laser alloyed Al-W coatings on aluminum for enhanced corrosion resistance

    Science.gov (United States)

    Rajamure, Ravi Shanker; Vora, Hitesh D.; Srinivasan, S. G.; Dahotre, Narendra B.

    2015-02-01

    A tungsten precursor deposit was spray coated on aluminum 1100 substrate and was subsequently surface alloyed using a continuous wave diode-pumped ytterbium laser at varying laser energy densities. For the laser energy input of 21-32 J/mm2 the melt depth ranged between 135 and 150 μm. Scanning electron microscopy observations indicated the formation of uniform and continuously dense laser alloyed coatings with sound interface between the modified surface and substrate along with an equi-axed grain structure with second phase precipitates in the intergranular region. X-ray diffraction analysis confirmed that laser processing has resulted in the formation of Al4W, as the major phase with retention of W in Al within the alloyed region. The corrosion resistance of laser alloyed coatings was evaluated in near natural chloride solution using ac and dc electrochemical techniques. After laser processing potential-time measurements has indicated the relatively stable and high potential values over the longer exposure times. Cyclic polarization results showed the reduction in the corrosion current density by a factor of 8, compared to untreated Al 1100. Besides, the electrochemical impedance spectroscopy confirmed the increase in the total resistance (47-70 kΩ cm2) with the increase in the laser energy density.

  4. Laser direct marking applied to rasterizing miniature Data Matrix Code on aluminum alloy

    Science.gov (United States)

    Li, Xia-Shuang; He, Wei-Ping; Lei, Lei; Wang, Jian; Guo, Gai-Fang; Zhang, Teng-Yun; Yue, Ting

    2016-03-01

    Precise miniaturization of 2D Data Matrix (DM) Codes on Aluminum alloy formed by raster mode laser direct part marking is demonstrated. The characteristic edge over-burn effects, which render vector mode laser direct part marking inadequate for producing precise and readable miniature codes, are minimized with raster mode laser marking. To obtain the control mechanism for the contrast and print growth of miniature DM code by raster laser marking process, the temperature field model of long pulse laser interaction with material is established. From the experimental results, laser average power and Q frequency have an important effect on the contrast and print growth of miniature DM code, and the threshold of laser average power and Q frequency for an identifiable miniature DM code are respectively 3.6 W and 110 kHz, which matches the model well within normal operating conditions. In addition, the empirical model of correlation occurring between laser marking parameters and module size is also obtained, and the optimal processing parameter values for an identifiable miniature DM code of different but certain data size are given. It is also found that an increase of the repeat scanning number effectively improves the surface finish of bore, the appearance consistency of modules, which has benefit to reading. The reading quality of miniature DM code is greatly improved using ultrasonic cleaning in water by avoiding the interference of color speckles surrounding modules.

  5. Crystalline garnet Bragg reflectors for high power, high temperature, and integrated applications fabricated by multi-beam pulsed laser deposition

    OpenAIRE

    Sloyan, Katherine A.; May-Smith, Timothy C.; Zervas, Michalis N.; Eason, Robert W.

    2012-01-01

    Crystalline Bragg reflectors are of interest for high power, high temperature and integrated applications. We demonstrate the automated growth of such structures by shuttered multi-beam Pulsed Laser Deposition (PLD). Geometries include 145 layer stacks exhibiting >99.5% reflection and ? phase-shifted designs. A crystalline grating strength-apodized sample was grown by mixing plumes to obtain layers with custom refractive indices. Peak reflection wavelength was tuneable with incident position,...

  6. Laser alloyed Al-W coatings on aluminum for enhanced corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Rajamure, Ravi Shanker; Vora, Hitesh D.; Srinivasan, S.G.; Dahotre, Narendra B., E-mail: Narendra.Dahotre@unt.edu

    2015-02-15

    Highlights: • Al{sub 4}W intermetallic phase was formed after laser surface alloying. • Potential–time measurements show the stable behavior after laser surface alloying. • Cyclic polarization indicates increase in corrosion resistance after laser surface alloying. - Abstract: A tungsten precursor deposit was spray coated on aluminum 1100 substrate and was subsequently surface alloyed using a continuous wave diode-pumped ytterbium laser at varying laser energy densities. For the laser energy input of 21–32 J/mm{sup 2} the melt depth ranged between 135 and 150 μm. Scanning electron microscopy observations indicated the formation of uniform and continuously dense laser alloyed coatings with sound interface between the modified surface and substrate along with an equi-axed grain structure with second phase precipitates in the intergranular region. X-ray diffraction analysis confirmed that laser processing has resulted in the formation of Al{sub 4}W, as the major phase with retention of W in Al within the alloyed region. The corrosion resistance of laser alloyed coatings was evaluated in near natural chloride solution using ac and dc electrochemical techniques. After laser processing potential–time measurements has indicated the relatively stable and high potential values over the longer exposure times. Cyclic polarization results showed the reduction in the corrosion current density by a factor of 8, compared to untreated Al 1100. Besides, the electrochemical impedance spectroscopy confirmed the increase in the total resistance (47–70 kΩ cm{sup 2}) with the increase in the laser energy density.

  7. Laser Assisted Additively Manufactured Transition Metal Coating on Aluminum

    Science.gov (United States)

    Vora, Hitesh D.; Rajamure, Ravi Shanker; Roy, Anurag; Srinivasan, S. G.; Sundararajan, G.; Banerjee, Rajarshi; Dahotre, Narendra B.

    2016-07-01

    Various physical and chemical properties of surface and subsurface regions of Al can be improved by the formation of transition metal intermetallic phases (Al x TM y ) via coating of the transition metal (TM). The lower equilibrium solid solubility of TM in Al (engineering via a laser-aided additive manufacturing approach can effectively synthesize TM intermetallic coatings on the surface of Al. The focus of the present work included the development of process control to achieve thermodynamic and kinetic conditions necessary for desirable physical, microstructural and compositional attributes. A multiphysics finite element model was developed to predict the temperature profile, cooling rate, melt depth, dilution of W in Al matrix and corresponding micro-hardness in the coating, and the interface between the coating and the base material and the base material.

  8. Microstructural and hardness investigation of an aluminum-copper alloy processed by laser surface melting

    International Nuclear Information System (INIS)

    Laser material processing has been widely applied in industrial processes due to the unique precision and very localized thermal action furnished by the laser's high energy density and power controllability. The scanned laser beam can be used to induce melting of a thin layer on metal surface when operated at higher intensity than that used for hardening. With the inherent rapid heating and cooling rates to which this surface layer is submitted, this process provides an opportunity to produce different microstructures from that of the bulk metal leading to useful properties. The major microstructural changes commonly observed in aluminum alloys are the extension of the solid solubility and the refinement of the microstructure. The objective of the current work was to analyze the microstructural and hardness variations throughout samples of an aluminum-copper alloy (Al-15 wt.% Cu) submitted to a laser surface remelting treatment. The analysis procedure consisted of scanning electron microscopy (SEM) characterization and microhardness tests in the resolidified and unmelted substrate regions

  9. Optimal power settings of aluminum gallium arsenide lasers in caries inhibition — An in vitro study

    Science.gov (United States)

    Sharma, Sonali; Hegde, Mithra N; Sadananda, Vandana; Mathews, Blessen

    2016-01-01

    Context: Incipient carious lesions are characterized by subsurface dissolution due to more fluoride ions in the 50-100 microns of the tooth's outer surface. Aims: To determine an optimal power setting for 810 nm aluminum gallium arsenide laser for caries inhibition. Materials and Methods: Fifty-four caries-free extracted teeth were sectioned mesiodistally. The samples were divided into 18 groups for each power setting being evaluated. Each group had six samples. The laser used is 810 nm aluminum gallium arsenide laser with power setting from 0.1 watts to 5 watts. Laser fluorescence based device was used to evaluate the effect of irradiation. Statistical Analysis Used: Paired “t” test, one-way analysis of variance (ANOVA), Tukey's post hoc test, and the Pearson's correlation test. Results: The paired t-test showed that there is minimum divergence from the control for 3.5 watts. Tukey's post hoc test also showed statistically significantly results for 3.5 watts. The Pearson's correlation test showed that there was negative correlation between the watts and irradiation. Conclusions: The power setting that gave statistically significant results was 3.5 watts. PMID:27099427

  10. High level compressive residual stresses produced in aluminum alloys by laser shock processing

    International Nuclear Information System (INIS)

    Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm2 in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm. Results using pulse densities of 2500 pulses/cm2 in 6061-T6 aluminum samples and 5000 pulses/cm2 in 2024 aluminum samples are presented. High level of compressive residual stresses are produced -1600 MPa for 6061-T6 Al alloy, and -1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products

  11. CO2 laser welding of aluminum alloys at high speeds up to 20 m/min

    Science.gov (United States)

    Takahashi, Kunimitsu; Kumagai, Mikio; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    CO2 laser welding of thin aluminum sheets was performed at welding speeds of up to 20 m/min to investigate the weldability, weld pool dynamics and mechanical properties of the weld bead of aluminum alloys. High-speed camera observation of weld areas showed that the thickness of the keyhole-front-face decreased to 100 μm under high-speed welding conditions and the weld pool became unstable. The focal length was optimized to increase the spot power density and thereby easily melt the aluminum sheets. Using a 76-mm focal length lens, which corresponds to 11 MW/cm2 power density, we obtained a keyhole mode weld bead with a depth of 1.3 mm at 20 m/min welding speed at 2 kW laser power. It was also possible to reduce the heat affected zone (HAZ) width to only 1.6 mm when the welding speed was 20 m/min. The HAZ width decreased as welding speed was increased. The tensile strength test of A6N01 weld beads showed that the fracture strength increased as the welding speed was increased up to 16 m/min, probably because the soft region of weld specimens was decreased. On the other hand, solidification cracks formed in the weld bead center at higher speeds, resulting in decreased strength.

  12. Multilayered polycrystalline iron garnet structure of Bi3Fe5O12 and Y3Fe5O12 grown on SiO2 substrates by pulsed laser deposition

    International Nuclear Information System (INIS)

    Iron Garnet single crystals like Y3Fe5O12 (YIG) are important ceramic systems with extensive applications in structural ceramics and optoelectronics. Currently, it is desirable to integrate such macroscopic components on a single chip (e.g. Si, SiO2,..) as in the case of microelectronics (integrated optics). High quality magnetooptical (MO) active garnet films with high Faraday rotation are also needed for MO imaging and microscopy. In our work we studied the influence of parameters during the deposition of YIG films and developed a new way to grow polycrystalline Bi3Fe5O12 (BIG) thin films on different SiO2 substrates using the pulsed laser deposition (PLD) method. Therefore we deposited a YIG buffer which was annealed above 1000 C in order to form a polycrystalline phase. On top of this buffer layer we deposited a thermodynamical unstable BIG layer. We measured the Faraday rotation of the films and studied them with x-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Environmental Scanning Electron Microscopy (ESEM) and high-resolution transmission electron spectroscopy (HRTEM). Their Faraday rotation can be compared with epitaxial BIG films grown on garnet substrates

  13. Radiation effects on the laser ablative shockwaves from aluminum under atmospheric conditions

    International Nuclear Information System (INIS)

    The evolution of laser ablative shockwaves (LASW) from Aluminum under atmospheric pressures is numerically modeled using a one-dimensional, three-temperature (electron, ion and thermal radiation temperatures), non-equilibrium, radiation hydrodynamic (RHD) model. The governing RHD equations in Lagrangian form are solved by using an implicit scheme. Similarly, the energy relaxation between the electrons and ions and the electrons and thermal radiation are determined implicitly. Apart from these, the energy equation takes into account the flux-limited electron thermal heat flux. The RHD equations are closed by using a two temperature QEOS model for the Al. The MULTI-fs code is modified to incorporate the nanosecond laser absorption model via the photoionization (PI) and the inverse bremsstrahlung (IB) processes. The spatio-temporal evolution of the laser ablative shockwaves generated by focusing a second harmonic (532 nm, 7ns) of Nd:YAG laser on to Aluminum target under atmospheric pressures in air is captured using a shadowgraphy technique. These measurements are made from 200 ns to 10 μs after the laser pulse with a temporal resolution of 1.5 ns. We report the details of the RHD model and compare the simulated and experimental results for input laser energies in the range of 25 - 175 mJ per pulse. The evolution of the plasma parameters like electron density, charge states and the shockwaves launched into the ambient atmosphere due to expanding plasma plume are compared. The role of thermal radiation on the evolution of LASW from Al is discussed. (author)

  14. Experimental Study Of Polyformaldehyde Propellants Seeded With Micron-Scale Aluminum Powder For Laser Propulsion

    International Nuclear Information System (INIS)

    The propulsion performance of polyoxymethylene (POM) seeded with micron-scale aluminum (μAl) powder has been studied experimentally with CO2 lasers. The results show that the momentum coupling coefficient (Cm) and specific impulse (Isp) of POM seeded with μAl powder is almost the same as pure POM at lower power density (6 W/cm2). At higher power density (>1·7xl06 W/cm2), Cm of POM seeded with μAl powder decreases significantly while Isp increases significantly. When this material is put into a cylindrical nozzle, the measured maximum Cm and Isp can raise to 40.1 dyne/W and 1361 s, respectively. The energy usage ratio is over 100%, which indicates that the aluminum powder may react chemically with the air under the constraint condition. This conclusion was verified experimentally both in atmosphere and vacuum conditions.

  15. Mechanism of laser welding of SiC reinforced LD2 aluminum metal matrix composite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper the mechanism of SiCP/LD2 aluminum matrix composites during laser welding was investigated. The emphasis was laid on the study of the distribution of aluminum carbides in whole welds. The joint can be divided into three regions both in depth and in width. The depth is divided into severe reaction region, partial reaction region, and no reaction region. In these regions, the extent of interfacial reaction varies gradually, the shape of reactants varies from long to fine. In width it can also be divided into severe reaction region, partial reaction region, and initial reaction region from the center of the weld to about the welding junction. In the initial reaction region, nucleation and growth of the reaction products on the surface of SiC particles can be observed by using TEM. The investigation showed that the quantity and size of SiC are relative to the temperature gradient in the molten pool.

  16. Quantitative analysis of impurities in aluminum alloys by laser-induced breakdown spectroscopy without internal calibration

    Institute of Scientific and Technical Information of China (English)

    LI Hong-kun; LIU Ming; CHEN Zhi-jiang; LI Run-hua

    2008-01-01

    To develop a fast and sensitive alloy elemental analysis method, a laser-induced breakdown spectroscopy(LIBS) system was established and used to carry out quantitative analysis of impurities in aluminum alloys in air at atmospheric pressure. A digital storage oscilloscope was used as signal recording instrument, instead of traditional gate integrator or Boxcar averager, to reduce the cost of the whole system. Linear calibration curves in the concentration range of 4×10-5-10-2 are built for Mg, Cr, Mn, Cu and Zn using absolute line intensity without internal calibrations. Limits of detection for these five elements in aluminum alloy are determined to be (2-90)×10-6. It is demonstrated that LIBS can provide quantitative trace elemental analysis in alloys even without internal calibration. This approach is easy to use in metallurgy industries and relative research fields.

  17. Effect of Yttrium Aluminum Garnet on High-Temperature Properties of Alumina-Based Ceramic Cores%钇铝石榴石对氧化铝基陶瓷型芯高温性能的影响

    Institute of Scientific and Technical Information of China (English)

    徐东阳; 李涤尘; 吴海华; 邢建东; 孙博

    2011-01-01

    开发了一种钇溶胶为强化剂、通过真空压力浸渍强化处理改善氧化铝基陶瓷型芯高温性能的新工艺.研究了浸渍工艺对陶瓷型芯高温性能的影响,利用x射线衍射和SEM分析了陶瓷型芯相组成及其断口形貌.实验结果表明高温性能随着浸渍次数的增加而得到明显地改善.三次浸渍强化后,高温挠度从7.38 mm降低至0.72 mm,高温抗弯强度(1550℃)从0.95MPa提高至4.6lMPa,而显气孔率仍保持在40%以上,保证了脱芯工艺性.X射线衍射分析表明真空压力浸渍之后增加了陶瓷型芯中耐高温强化相-钇铝石榴石的含量,SEM观察也证实了这一点.%A new strengthening process was developed to improve the high-temperature properties of alumina-based ceramic cores by vacuum pressure impregnation (VPI) with yttrium sol as reinforcing agent. The experimental results showed that the high-temperature properties of the cores were improved significantly as impregnating times increasing. After three times impregnation strengthening, the deformation at 1550℃/0.5h decreased from 7.38 mm to 0. 72 mm and the flexural strength at 1550℃ increased from 0.95MPa to 4.61 MPa. Meanwhile the apparent porosity still kept above 40% to guarantee the core leach property. X-ray diffraction revealed that the content of YAG( yttrium aluminum garnet, a high-temperature strengthening phase)was increased through VPI, which was obviously observed by SEM.

  18. Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    HUANG Kaijin; LIN Xin; XIE Changsheng; T M Yue

    2008-01-01

    Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hard a-Al2O3 and γ-Al2O,3phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.

  19. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Sabina Luisa Campanelli

    2013-12-01

    Full Text Available Friction Stir Welding (FSW is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  20. Porosity evolution in aluminum alloy 2024 bop and butt defocused welding by Yb-YAG disk laser

    OpenAIRE

    Alfieri, Vittorio; Cardaropoli, Francesco; Caiazzo, Fabrizia; Sergi, Vincenzo

    2011-01-01

    In many industrial applications, in order to obtain good results in laser welding processes, it may not be sufficient to use a focused beam on the upper surface, so a defocused beam is required instead. This study aims to investigate which advantages a defocused beam may offer in welding aluminum alloy 2024 using Yb:YAG disk laser. A characterization of laser beam geometry is preliminary necessary, in order to correlate bead features and effective specific energy provided. Porosity content de...

  1. Investigation of the local thermodynamic equilibrium of laser-induced aluminum plasma by Thomson scattering technique

    Energy Technology Data Exchange (ETDEWEB)

    Mendys, A., E-mail: agata.mendys@uj.edu.pl [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); Kański, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); Farah-Sougueh, A. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); GREMI — site de Bourges, Université d' Orléans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France); Pellerin, S. [GREMI — site de Bourges, Université d' Orléans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France); Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ul. Podchorażych 2, 30-084 Kraków (Poland); Dzierżęga, K. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland)

    2014-06-01

    A laser Thomson scattering method was applied to investigate the local Saha–Boltzmann equilibrium in aluminum laser-induced plasma. Plasma was created in ambient air using 4.5 ns pulses from a Nd:YAG laser at 532 nm, focused on an Al target. Spatially resolved measurements, performed for the time interval between 600 ns and 3 μs, show electron density and temperature to decrease from 3.4 × 10{sup 23} m{sup −3} to 0.5 × 10{sup 23} m{sup −3} and from 61,000 K to 13,000 K in the plasma core. The existence of local thermodynamic equilibria in the plasma was verified by comparing the rates of the collisional to radiative processes (the McWhirter criterion), as well as relaxation times and diffusion lengths of different plasma species, with the appropriate rate of electron density evolution and its gradients at given, experimentally determined, electron temperatures. We found these criteria to be much easier to satisfy for metallic plasma species than for nitrogen. The criteria are also easier to satisfy in the plasma core of higher electron density. - Highlights: • Laser Thomson scattering method was applied to investigate aluminum laser-induced plasma. • Spatio-temporal evolution of electron temperature and density was determined. • Three criteria for existence of local thermodynamic equilibrium were verified. • Criteria are much easier to satisfy for metallic plasma species than for nitrogen. • Criteria are easier to satisfy at earlier times and in the plasma core.

  2. An Investigation of Laser Assisted Machining of Al_2O_3 Particle Reinforced Aluminum Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Al 2O 3 particles reinforced aluminum matrix composite (Al 2O 3p/Al) are more and more widely used for their excellent physical and chemical properties. However, their poor machinability leads to severe tool wear and bad machined surface. In this paper laser assisted machining is adopted in machining Al 2O 3p/Al composite and good result was obtained. The result of experiment shows in machining Al 2O 3p/Al composites the cutting force is reduced in 30%~50%, the tool wear is reduced in 20%~30% an...

  3. Spectroscopic analysis of element concentrations in aluminum alloy using nanosecond laser-induced breakdown spectroscopy

    Science.gov (United States)

    Luo, Wenfeng; Tang, Jie; Gao, Cunxiao; Wang, Haojing; Zhao, Wei

    2010-06-01

    A plasma generated by 1064 nm Nd:YAG laser irradiation of aluminum alloy in air at atmospheric pressure was studied spectroscopically. The electron density was inferred by measuring the Stark broadened line profile of Cu(I) 324.75 nm, while the electron temperature was determined using the Boltzmann plot method with ten neutral iron lines. Based on the results, local thermodynamic equilibrium was studied. Moreover, calibration curves were presented for samples containing Si, Fe, Cu, Mn, Mg, Ni, Zn and Ti, and the limit of detection of trace elements was calculated based on experimental results.

  4. Combined laser and atomic force microscope lithography on aluminum: Mask fabrication for nanoelectromechanical systems

    DEFF Research Database (Denmark)

    Berini, Abadal Gabriel; Boisen, Anja; Davis, Zachary James;

    1999-01-01

    A direct-write laser system and an atomic force microscope (AFM) are combined to modify thin layers of aluminum on an oxidized silicon substrate, in order to fabricate conducting and robust etch masks with submicron features. These masks are very well suited for the production of nanoelectromecha...... writing, and to perform submicron modifications by AFM oxidation. The mask fabrication for a nanoscale suspended resonator bridge is used to illustrate the advantages of this combined technique for NEMS. (C) 1999 American Institute of Physics. [S0003-6951(99)00221-1]....

  5. Direct observation of keyhole plasma characteristics in deep penetration laser welding of aluminum alloy 6016

    International Nuclear Information System (INIS)

    Deep penetration laser welding is associated with violent plasma generation which consists of metal vapour, ionized ions and electrons. The plasma resides both outside and inside the keyhole, known as the plasma plume and keyhole plasma, respectively. Plasma plumes have been studied extensively due to the convenience of observing them. However, very little work has been carried out on the investigation of keyhole plasmas. In this paper, a novel experimental set-up is designed to observe the keyhole plasma directly in CW and PW deep penetration laser welding of aluminum alloy 6016. Then on the basis of the experimentally obtained spectra, the electron temperature distribution of the keyhole plasma both in the radial and depth directions of the keyhole is calculated, and the effects of processing parameters such as laser power, welding velocity and defocus on the keyhole plasma temperature are studied. The results show that the electron temperature of the keyhole plasma both in the radial and depth directions is not uniformly distributed. The temperature increases as the laser power increases, decreases as the welding velocity increases and decreases as the location of the laser beam focal point is moved from within to above the keyhole. (paper)

  6. Detailed diagnostics of a laser produced aluminum plasma by the Kα satellites

    International Nuclear Information System (INIS)

    A most recent measurement of the Kα opacity of a laser produced aluminum plasma [Xu Y, Zhang J, Yang J, Pei W, Ding Y, Lai D, et al. A clean radiation environment for opacity measurements of radiatively heated material. Phys Plasmas 2007;14:052701-5] has been theoretically studied by a detailed level accounting (DLA) model. The Kα lines both of Li-like and Be-like aluminum were calculated and used to perform detailed diagnostics to the plasma temperature. Atomic levels and oscillator strengths of the relevant ions were generated by solving the fully relativistic Dirac-Fock equation with configuration interaction within one-configuration being considered. Since the experimental plasma was well kept in local thermodynamic equilibrium (LTE), we solve the Saha equations to calculate the populations both between and within charge states. The aluminum plasma has reached so high a temperature of about 95 eV that the populations of the Rydberg states of the Li-like and Be-like ions become considerably large and the Kα satellites become the dominating features. By best fitting to the measured spectrum the plasma temperature is determined to be 95 eV. However fairly large uncertainties of ±5eV are found

  7. Study of Interaction of Laser with Tissue Using Monte Carlo Method for 1064nm Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

    OpenAIRE

    Majdabadi, Abbas; Abazari, Mohammad

    2015-01-01

    Introduction: Liposuction using laser is now one of the most common cosmetic surgery. This new method has minimized the disadvantages of the conventional liposuction including blood loss, skin laxity and long recovery time. Benefits of the new liposuction methods which include less trauma, bleeding and skin tightening prove the superiority of these methods over the traditional mechanical methods. Interaction of laser with fat tissue has the vital role in the development of these new procedure...

  8. Molecular dynamics simulations of cluster distribution from femtosecond laser ablation in aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Sonntag, S.; Trichet Paredes, C.; Roth, J.; Trebin, H.R. [University of Stuttgart, Institute for Theoretical and Applied Physics, Stuttgart (Germany)

    2011-08-15

    Femtosecond laser ablation and plume evolution of aluminum is investigated for various inhomogeneous laser pulses. For the simulations of the atoms the molecular dynamics code IMD is used. The ablated gas-phase is scanned by a cluster algorithm (DBSCAN), from which we gain a cluster size distribution of the ablated material. Per single pulse, only a small portion of the total volume evaporates into the gas phase. Therefore - to have reasonable statistics - we have to deal with huge samples (6 x 10{sup 7} atoms). The ablation threshold is determined by comparing the depth of the holes to the applied fluence. Angular and velocity distributions of the plume are compared to experiments. (orig.)

  9. Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

    International Nuclear Information System (INIS)

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.

  10. Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Baladi, Arash [Materials Engineering Department, Tarbiat Modares University, Jalal Al Ahmad, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Sarraf Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Materials Engineering Department, Tarbiat Modares University, Jalal Al Ahmad, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2010-10-01

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.

  11. Space-resolved diagnosis for electron temperature of laser-produced aluminum plasma

    International Nuclear Information System (INIS)

    The K-shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20 μm wide space-resolved slit. By using the approximation of the steady collisional-radiative equilibrium model, the interstage line intensity ratios of Ly-α resonance line to He-α resonance line are given as a function of electron temperature. The spectra profiles are decomposed to resonance line and the overlapped high-order satellites manifold. Thus reliable electron temperature is deduced from the interstage line intensity ratios of the decomposed resonance lines. The results of spaced-resolved temperature are compared with the hydrodynamic simulations. The diagnostics of electron temperature for laser-produced plasma is developed. (authors)

  12. Space-Resolved Diagnosis for Electron Temperature of Laser-Produced Aluminum Plasma

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yang; ZHANG Ji-Yan; YANG Jia-Min; DENG Bo; XIONG Gang; HU Zhi-Min; WEI Min-Xi; ZHU Tuo; SHANG Wan-Li; LI Jun; YANG Guo-Hong

    2011-01-01

    @@ The K-shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20μm wide space-resolved slit.By using the approximation of the steady collisional-radiatiye equilibrium model, the interstage line intensity ratios of Ly-α resonance line to He-α resonance line are given as a function of electron temperature.The spectra profiles are decomposed to resonance line and the overlapped high-order satellites manifold.Thus reliable electron temperature is deduced from the interstage line intensity ratios of the decomposed resonance lines.The results of spaced-resolved temperature are compared with the hydrodynamic simulations.The diagnostics of electron temperature for laser-produced plasma is developed.

  13. Laser assembly nanostructured Al2O3/TiO2 coating on cast aluminum surface

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guang-jun; DAI Jian-qiang; WANG Hui-ping; YAN Min-jie; XI Wen-long; ZOU Chang-gu; GE Da-fang

    2004-01-01

    CO2 laser quick assembly technology is adopted on the surface of cast aluminum ZL104 to form a dense ceramic coating containing a great deal of nanometer Al2O3/TiO2 particles which eliminate cracks and porosities.The major phases of the coating are α-Al2O3 andβ-TiO2. The micro-hardness distribution of the coating is 1 813,1 504, 1 485 and 1 232 (HV0.05). The bonding strength of the coating LC1 is 11.4 N, which is 7.26 times higher than that of the conventional hot-spraying Al2O3/TiO2 coating. It has been proved by analysis that the bonding strength is achieved because of the effects of both super-quick laser consolidation and the nanometer effect of nanometer ceramic material.

  14. UV excimer laser photoproducts from absorbing and transparent surfaces covered by aluminum alkyl adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Stuke, M. (Max-Planck-Institut fuer Biophysikalische Chemie, Goettingen (Germany, F.R.))

    1989-06-01

    Neutral atomic and molecular species, generated upon the interaction of UV excimer laser light with Al-alkyl/substrate interfaces, are detected by single-shot dye laser mass spectroscopy. The molecules studied at 308, 248, and 193 nm are trimethylaluminum (TMA), triethylaluminum (TEA), and triisobutylaluminum (TIBA). The substrate is either n-type Si(100) or SiO{sub 2} (quartz). The major aluminum-containing species detected are Al atoms and AlH and AlCH{sub 3} molecules. Their relative abundance is shown to depend on the absorbate molecule and the wavelength chosen. Marked differences are observed between the case of the Al-alkyls photolyzed under collision-free conditions in the gas phase and when these molecules are adsorbed to a substrate.

  15. Electron dynamics and prompt ablation of aluminum surface excited by intense femtosecond laser pulse

    Science.gov (United States)

    Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Seleznev, L. V.; Sinitsyn, D. V.

    2014-12-01

    Thin aluminum film homogeneously heated by intense IR femtosecond laser pulses exhibits on the excitation timescale consequent fluence-dependent rise and drop of the IR-pump self-reflectivity, followed by its final saturation at higher fluences F > 0.3 J/cm2. This prompt optical dynamics correlates with the initial monotonic increase in the accompanying laser-induced electron emission, which is succeeded by its non-linear (three-photon) increase for F > 0.3 J/cm2. The underlying electronic dynamics is related to the initial saturation of IR resonant interband transitions in this material, followed by its strong instantaneous electronic heating via intraband transitions during the pump pulse resulting in thermionic emission. Above the threshold fluence of 0.3 J/cm2, the surface electronic heating is balanced during the pump pulse by simultaneous cooling via intense plasma removal (prompt ablation). The relationship between the deposited volume energy density in the film and its prompt electronic temperature derived from the self-reflection measurements using a Drude model, demonstrates a kind of electron "liquid-vapor" phase transition, driven by strong cubic optical non-linearity of the photo-excited aluminum.

  16. The feasibility of producing aluminum-lithium structures for cryogenic tankage applications by laser beam welding

    Science.gov (United States)

    Martukanitz, R. P.; Lysher, K. G.

    1993-01-01

    Aluminum-lithium alloys exhibit high strength, high elastic modulus, and low density as well as excellent cryogenic mechanical properties making them ideal material candidates for cryogenic tanks. NASA has proposed the use of 'built-up' structure for panels fabricated into cryogenic tanks replacing current conventional machining. Superplastically formed stiffeners would be joined to sheet (tank skin) that had been roll formed to the radius of the tank in order to produce panels. Aluminum-lithium alloys of interest for producing the built-up structure include alloy 2095-T6 stiffeners to 2095-T8 sheet and alloy 8090-T6 stiffeners to 2090-T83 sheet. Laser welding, with comparable joint properties, offers the following advantages over conventional welding: higher production rates, minimal degradation within the heat affected zones, and full process automation. This study established process parameters for laser beam welding, mechanical property determinations, metallographic characterization, and fabrication of prototype panels. Tensile tests representing partial penetration of the skin alloys provided joint efficiencies between 65 and 77 percent, depending upon alloy and degree of penetration. Results of tension shear tests of lap welds indicated that the combination of 2095-T6 to 2090-T8 exhibited significantly higher weld shear strength at the interface in comparison to welds of 8090-T6 to 2090-T83. The increased shear strength associated with 2095 is believed to be due to the alloy's ability to precipitation strengthening (naturally age) after welding.

  17. Fabrication of titanium dental implants by selective laser melting

    Science.gov (United States)

    Santos, Edson; Osakada, Kozo; Shiomi, Masanori; Morita, Masanori; Abe, Fumie

    2004-10-01

    The present paper will discuss the influence of the processing parameters on the characteristics of titanium models built by Selective Laser Melting. The microstructure and the fatigue strength of the three dimensional titanium models formed by Selective Laser Melting with an Nd-yttritrium-aluminum-garnet (YAG) pulsed laser are investigated. In order to increase the wear resistance of titanium models, surface alloying via laser-gas-nitriding (LGN) is applied. The mechanical properties of the models built by laser forming are adequate for fabrication of dental implants.

  18. Urologic laser types and instrumentation.

    Science.gov (United States)

    Natalin, Ricardo A; Phillips, Courtney K; Clayman, Ralph V; Landman, Jaime

    2008-11-01

    Though the primary role of lasers in urology has always been in the treatment of urolithiasis, there are several other indications for their use. There are many different types of lasers currently available, each with unique properties conducive to treating certain disorders. As such, it is critical that today's urologist understands each laser's characteristics in order to optimize patient selection and treatment. The lasers which are primarily used in urologic applications include the carbon dioxide (CO2) laser; the Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG); the Potassium Titanyl Phosphate (KTP) laser and the Holmium:YAG (Ho:YAG) laser. This review focuses on the unique characteristics of each of these lasers as well as the instrumentation needed utilize and deploy these tools in the urinary tract. PMID:19140577

  19. A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

    Science.gov (United States)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

    Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

  20. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Canteli, D., E-mail: david.canteli@ciemat.es [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Fernandez, S. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Molpeceres, C. [Centro Laser, Universidad Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Torres, I.; Gandia, J.J. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. Black-Right-Pointing-Pointer The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. Black-Right-Pointing-Pointer A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 Degree-Sign C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  1. Laser induced breakdown spectroscopy of pure aluminum with high temporal resolution.

    Science.gov (United States)

    Li, Yu-Tai; Liu, Tze-An; Chen, Chen-Wei; Lee, Yu-Hsien; Yabushita, Atsushi

    2013-09-01

    We report on a Laser Induced Breakdown Spectroscopy (LIBS) system with a very high temporal resolution, using femtosecond and picosecond pulse laser excitation of pure aluminum (Al). By using a 140 fs Ti:Sapphire laser in an ultrafast optical Kerr gate (OKG), we demonstrate LIBS sampling with a sub-ps time resolution (0.8 ± 0.08 ps) in a 14 ns window. The width of the gating window in this system was as narrow as 0.8 ps, owing to the inclusion of a carbon disulfide (CS(2)) cell, which has a fast response and a large nonlinear coefficient. Furthermore, when using a 100 ps pulsed Nd:YAG laser and a fast photomultiplier tube (PMT) we demonstrate a LIBS system with a nanosecond time resolution (2.20 ± 0.08 ns) in a microsecond window. With this sort of temporal resolution, a non-continuous decay in the Al signal could be observed. After 50 ns decay of the first peak, the second peak at 230 ns is started to perform. Experimental results with such short temporal windows in LIBS, in both nanosecond and microsecond ranges, are important for fast temporal evolution measurements and observations of early continuum emission in materials. PMID:24104032

  2. Non-contact sheet forming using lasers applied to a high strength aluminum alloy

    Directory of Open Access Journals (Sweden)

    Rafael Humberto Mota Siqueira

    2016-07-01

    Full Text Available Laser beam forming (LBF is a contactless mechanical process accomplished by the introduction of thermal stresses on the surface of a material using a laser in order to induce plastic deformation. In this work, LBF was performed on 1.6 mm thick sheets of a high strength aluminum alloy, AA6013-T4 class by using a defocused continuous Yb-fiber laser beam of 0.6 mm in diameter on the sheet top surface. The laser power and process speed were varied from 200 W to 2000 W and from 3 to 30 mm/s, respectively. For these experimental conditions, the bending angle of the sheet ranged from 0.1° to 2.5° per run. In the highest bending angle condition, 1000 W and 30 mm/s, the depth of remelted pool was 0.6 mm and the microstructure near the plate bottom surface remained unaltered. For the whole set of experimental conditions, the hardness remained constant at approximately 100 HV, which is similar to the base material. In order to verify the applicability of the method, some previously T-welded sheets were straightened. The method was efficient in correcting the distortion of the sheets with a bending angle up to 5°.

  3. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    International Nuclear Information System (INIS)

    Highlights: ► A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. ► The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. ► A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 °C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  4. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    International Nuclear Information System (INIS)

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al2O3 and Fe2O3. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe2O3, 20–40 nm) and aluminum oxide (Al2O3, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm2 with a concentration of 5 and 7 wt% of Fe2O3 presented the MgFe2O4 spinel-type phase. With the addition of Al2O3 nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm2, there were the formations of MgAl2O4 spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed

  5. Influence of pulsed Nd3+ : YAG laser beam profile and wavelength on microscribing of copper and aluminum thin films

    Science.gov (United States)

    Nammi, Srinagalakshmi; Vasa, Nilesh J.; Balaganesan, G.; Gupta, Sanjay; Mathur, Anil C.

    2015-10-01

    Evenly spaced conductive grids of copper and aluminum thin films on polyimide substrate are used for parabolic reflector antennas aboard telecommunications satellites. Laser microscribing of thin films using a flat-top and Gaussian laser beam profile is analyzed with 95% overlapping of the diameter of the laser spot. Laser scribing is performed using the Q-switched Nd3+: YAG (355, 532 nm) laser. The influence of laser irradiation and beam shape on the scribed microchannel width, depth, and surface characteristics is experimentally analyzed using a noncontact optical profilometer and scanning electron microscope (SEM). Laser scribing using a flat-top profile produced near rectangular microchannels in copper thin films. Using the Gaussian profile, the probability of melting is greater than vaporization as observed using SEM images; this melt pool plays a prominent role in resolidification at the edges. The depth of the scribe channel is observed to be 20% higher for the 532-nm wavelength compared to the 355-nm wavelength. The effect of different environments such as air, water, and vacuum on the channel depth and quality is reported. The response of aluminum and copper thin films for high fluences is also studied. Thermal modeling of the laser-material interaction has been attempted by assuming the plasma electron temperature as the laser ablation temperature for modeling the recession rate and depth for a single laser pulse. Model results agree with experimental data showing greater depth for 532 nm compared to 355 nm.

  6. Influence of erbium, chromium-doped: Yttrium scandium-gallium-garnet laser etching and traditional etching systems on depth of resin penetration in enamel: A confocal laser scanning electron microscope study

    Science.gov (United States)

    Vijayan, Vishal; Rajasigamani, K.; Karthik, K.; Maroli, Sasidharan; Chakkarayan, Jitesh; Haris, Mohamed

    2015-01-01

    Objective: This study was performed to assess the resin tag length penetration in enamel surface after bonding of brackets to identify which system was most efficient. Methodology: Our study was based on a more robust confocal microscopy for visualizing the resin tags in enamel. Totally, 100 extracted human first and second premolars have been selected for this study and were randomly divided into ten groups of 10 teeth each. In Group 1, the buccal enamel surface was etched with 37% phosphoric acid (3M ESPE), Group 2 with 37% phosphoric (Ultradent). In Groups 5, 6, and 7, erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser (Biolase) was used for etching the using following specifications: Group 5 (1.5 W/20 Hz, 15 s), Group 6 (2 W/10 Hz, 15 s), and Group 7 (2 W/20 Hz, 15 s). In Groups 8, 9, and 10, Er, Cr: YSGG laser (Biolase) using same specifications and additional to this step, conventional etching on the buccal enamel surface was etched with 37% (3M ESPE) after laser etching. In Groups 1, 5, 6, 7, 8, 9, and 10 3M Unitek Transbond XT primer was mixed with Rhodamine B dye (Sigma-Aldrich, Germany) to etched surface and then cured for 20 s. In Group 2, Ultradents bonding agent was mixed with Rhodamine B. In Group 3, 3M Unitek Transbond PLUS, Monrovia, USA, which was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Group 4, with self-etching primer (Ultradent-Peak SE, USA) was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Later (3M Unitek, Transbond XT, Monrovia USA) [Figure 1] was used to bond the modified Begg brackets (T. P. Orthodontics) in Groups 1, 3, 5, 6, 7, 8, 9, and 10. In Groups 2, 4 Ultradent-Peak LC Bond was used to bond the modified brackets. After curing brackets were debonded, and enamel depth penetration was assessed using confocal laser scanning microscope. Results: Group J had a mean maximum depth of penetration of 100.876 μm, and Group D was the least having a maximum value of 44.254 μm. Conclusions: Laser

  7. Effect of laser peening with different energies on fatigue fracture evolution of 6061-T6 aluminum alloy

    Science.gov (United States)

    Sheng, J.; Huang, S.; Zhou, J. Z.; Lu, J. Z.; Xu, S. Q.; Zhang, H. F.

    2016-03-01

    To deeply understand the effect of laser peening (LP) with different laser pulse energies on 6061-T6 aluminum alloy, the fatigue fracture morphologies evolution process at various fatigue crack growth (FCG) stages and the corresponding strengthen mechanism were investigated. At the initial stage of FCG, more fatigue micro-cliffs were found after LP, while the fatigue striation spacing simultaneously reduced. A "stop-continue" phenomenon of crack propagation was discovered for laser peened samples. The fatigue striation spacing at the middle stage of FCG increased significantly while compared with that at the initial stage, in addition, the fatigue striation spacing decreased with an increase in laser pulse energy. Fracture morphologies in transition region of laser peened samples exhibit a mixing fracture characteristic of striations and dimples. The laser peened sample with laser pulse energy of 7 J presents more circuitous growing paths. Due to the complex stress state induced by LP, dimples with different sizes appeared in the final fracture region.

  8. High-efficiency cavity-dumped micro-chip Yb:YAG laser

    Science.gov (United States)

    Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

    2014-09-01

    High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

  9. Laser-induced back-ablation of aluminum thin films using picosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK, A B

    1999-05-26

    Experiments were performed to understand laser-induced back-ablation of Al film targets with picosecond laser pulses. Al films deposited on the back surface of BK-7 substrates are ablated by picosecond laser pulses propagating into the Al film through the substrate. The ablated Al plume is transversely probed by a time-delayed, two-color sub-picoseond (500 fs) pulse, and this probe is then used to produce self-referencing interferograms and shadowgraphs of the Al plume in flight. Optical emission from the Al target due to LIBA is directed into a time-integrated grating spectrometer, and a time-integrating CCD camera records images of the Al plume emission. Ablated Al plumes are also redeposited on to receiving substrates. A post-experimental study of the Al target and recollected deposit characteristics was also done using optical microscopy, interferometry, and profilometry. In this high laser intensity regime, laser-induced substrate ionization and damage strongly limits transmitted laser fluence through the substrate above a threshold fluence. The threshold fluence for this ionization-based transmission limit in the substrate is dependent on the duration of the incident pulse. The substrate ionization can be used as a dynamic control of both transmitted spatial pulse profile and ablated Al plume shape. The efficiency of laser energy transfer between the laser pulse incident on the Al film and the ablated Al plume is estimated to be of order 5% and is a weak function of laser pulsewidth. The Al plume is highly directed. Low plume divergence ({theta}{sub divergence} < 5{sup o}) shows the ablated plume temperature to be very low at long time delays ( T << 0.5 eV at delays of 255 ns). Spectroscopic observations and calculations indicate that, in early time (t < 100 ps), the Al film region near the substrate/metal interface is at temperatures of order 0.5 eV. Interferograms of Al plumes produced with 0.1 {micro}m films show these plumes to be of high neutral atom

  10. Time-of-Flight Measurement of a 355-nm Nd:YAG Laser-Produced Aluminum Plasma

    Directory of Open Access Journals (Sweden)

    M. F. Baclayon

    2003-06-01

    Full Text Available An aluminum target in air was irradiated by a 355-nm Nd:YAG laser with a pulse width of 10 ns and arepetition rate of 10 Hz. The emission spectra of the laser-produced aluminum plasma were investigatedwith varying distances from the target surface. The results show the presence of a strong continuum veryclose to the target surface, but as the plasma evolve in space, the continuum gradually disappears and theemitted spectra are dominated by stronger line emissions. The observed plasma species are the neutraland singly ionized aluminum and their speeds were investigated using an optical time-of-flight measurementtechnique. Results show that the speeds of the plasma species decreases gradually with distance from thetarget surface. Comparison of the computed speeds of the plasma species shows that the singly ionizedspecies have relatively greater kinetic energy than the neutral species.

  11. Microstructure and corrosion properties of diode laser melted friction stir weld of aluminum alloy 2024 T351

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Samar Jyoti, E-mail: Samar.Kalita@und.nodak.edu [Engineered Surfaces Center, School of Engineering and Mines, University of North Dakota, Grand Forks, ND (United States)

    2011-02-15

    Friction stir welding is a promising solid state joining process for high strength aluminum alloys. Though friction stir welding eliminates the problems of fusion welding as it is performed below melting temperature (T{sub m}), it creates severe plastic deformation. Friction stir welds of some aluminum alloys exhibit relatively poor corrosion resistance. This research enhanced the corrosion properties of such welds through diode laser surface melting. A friction stir weld of aluminum alloy 2024 T351 was laser melted using a 1 kW diode laser. The melt-depth and microstructure were investigated using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. At the interface between the melted and the un-melted zone, a thick planar boundary was observed. Energy dispersive spectroscopy analyzed the redistribution of elemental composition. The corrosion properties of the laser melted and native welds were studied in aqueous 0.5 M sodium chloride solution using open circuit potential and cyclic potentiodynamic polarization. The results show noticeable increase in the pit nucleation resistance (390 mV) after the laser surface treatment. The repassivation potential was nobler to the corrosion potential after the laser treatment, which confirmed that the resistance to pit growth was improved.

  12. Microstructure and corrosion properties of diode laser melted friction stir weld of aluminum alloy 2024 T351

    International Nuclear Information System (INIS)

    Friction stir welding is a promising solid state joining process for high strength aluminum alloys. Though friction stir welding eliminates the problems of fusion welding as it is performed below melting temperature (Tm), it creates severe plastic deformation. Friction stir welds of some aluminum alloys exhibit relatively poor corrosion resistance. This research enhanced the corrosion properties of such welds through diode laser surface melting. A friction stir weld of aluminum alloy 2024 T351 was laser melted using a 1 kW diode laser. The melt-depth and microstructure were investigated using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. At the interface between the melted and the un-melted zone, a thick planar boundary was observed. Energy dispersive spectroscopy analyzed the redistribution of elemental composition. The corrosion properties of the laser melted and native welds were studied in aqueous 0.5 M sodium chloride solution using open circuit potential and cyclic potentiodynamic polarization. The results show noticeable increase in the pit nucleation resistance (390 mV) after the laser surface treatment. The repassivation potential was nobler to the corrosion potential after the laser treatment, which confirmed that the resistance to pit growth was improved.

  13. Spectroscopic diagnostics of ionization balance and electron density in 20 picosecond laser-produced aluminum and magnesium plasmas

    International Nuclear Information System (INIS)

    A quasi-steady state, collisional-radiative model is used to analyze spectra from aluminum and magnesium plasmas produced by irradiation with 20 picosecond pulses of 0.53μ laser light. The model infers the ionization balance and electron density of a plasma from the relative intensities of H-like and He-like x-ray transitions

  14. The Incidence of Hypertrophic Scarring and Keloid Formation Following Laser Tattoo Removal with a Quality-switched Nd:YAG Laser

    Science.gov (United States)

    Alston, Dylan B.; Chen, Alan H.

    2016-01-01

    Background: Laser tattoo removal using quality switched technology is widely accepted as the standard of care. Determining the risk of hypertrophic scarring and keloid formation more precisely delineates the safety of this procedure and improves patient education regarding the risk of scarring. Objective: To investigate the incidence of hypertrophic scarring and keloids in a large patient population following treatment with a Q-switched neodymium-doped:yttrium-aluminum-garnet laser. Design: In November 2012, after a single Institutional Review Board approved retrospective chart review, 1,041 charts demonstrating greater than five treatment sessions were analyzed. All patients in the current retrospective study were treated under one study protocol. Results: An overall incidence of 0.28 percent (3/1,041) of patients receiving a minimum of five laser tattoo treatments with a Q-switched neodymium-doped:yttrium-aluminum-garnet laser developed clinical evidence of hypertrophic scarring. None of the 1,041 patients in this study developed keloid scars. Conclusion: With the Q-switched neodymium-doped:yttrium-aluminum-garnet laser utilizing accurate, protocol-based settings, the incidence of hypertrophic scarring following laser tattoo removal treatments was 0.28 percent (3/1,041) and the incidence of keloid scarring was 0.00 percent (0/1,041). PMID:27386045

  15. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser.

    Science.gov (United States)

    Zhou, Binbin; Wei, Zhiyi; Zou, Yuwan; Zhang, Yongdong; Zhong, Xin; Bourdet, G L; Wang, Junli

    2010-02-01

    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope efficiency of 76%. Our measurement showed that the pulse duration was 418 fs with the central wavelength of 1048 nm. PMID:20125697

  16. Joint performance of laser-TIG double-side welded 5A06 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-bin; MIAO Yu-gang; LI Li-qun; WU Lin

    2009-01-01

    The influence of welding parameters on mechanical properties and microstructure of the welds of laser-TIG double-side welded 5A06 aluminum alloy was investigated. The results show that the weld cross-sectional shape has an intimate relation with the mechanical properties and microstructure of the welds. The symmetrical "X" cross-section possesses a relatively higher tensile strength and elongation than the others, about 91% and 58% of those of base metal, respectively. The good weld profiles and free defects are responsible for the improvement of tensile properties. Due to low hardness of the fusion zone, this region is the weakest area in the tensile test and much easier to fracture. The loss of Mg element is responsible for the decrease of mechanical properties of the joints. The microstructure of "X" cross-section has an obvious difference along the direction of weld depth, and that of the "H" cross-section is consistent and coarse.

  17. Studies of aluminum oxide thin films deposited by laser ablation technique

    Science.gov (United States)

    Płóciennik, P.; Guichaoua, D.; Korcala, A.; Zawadzka, A.

    2016-06-01

    This paper presents the structural and optical investigations of the aluminum oxide nanocrystalline thin films. Investigated films were fabricated by laser ablation technique in high vacuum onto quartz substrates. The films were deposited at two different temperatures of the substrates equal to room temperature and 900 K. X-ray Diffraction spectra proved nanocrystalline character and the corundum phase of the film regardless on the substrate temperature during the deposition process. Values of the refractive indices, extinction and absorption coefficients were calculated by using Transmission and Reflection Spectroscopy in the UV-VIS-NIR range of the wavelength. Coupling Prism Method was used for films thickness estimations. Experimental measurements and theoretical calculations of the Third Harmonic Generation were also reported. Obtained results show that the lattice strain may affect obtained values of the third order nonlinear optical susceptibility.

  18. Warm dense aluminum plasma generated by the free-electron-laser FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Zastrau, U.; Vinko, S. M.; Wark, J. S.; Toleikis, S.; Tschentscher, T.; Glenzer, S. H.; Lee, R. W.; Nelson, A. J.; Dzelzainis, T. W. J.; Riley, D.; Nagler, B.; Galtier, E.; Rosmej, F. B.; Foerster, E. [IOQ, Friedrich-Schiller-Universitaet, Max-Wien Platz 1, 07743 Jena (Germany); Clarendon Laboratory, University of Oxford, South Parks Road OX1 3PU (United Kingdom); Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22603 Hamburg (Germany); European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); School of Mathematics and Physics, QueenSs University, Belfast, Belfast BT7 1NN (United Kingdom); SLAC, National Accelerator Laboratory, 2575 Sand Hill Road, California 94025 (United States); Universites, Pierre et Marie Curie, LULI, UMR 7605, 75252 Paris Cedex 05 (France); Helmholtz Institut Jena, Helmholtzweg 4, 07743 Jena (Germany)

    2012-05-25

    We report on experiments aimed at the generation and characterization of solid density plasmas at the free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses at 13.5 nm wavelength (92 eV photon energy). The pulses with duration of a few tens of femtoseconds and pulse energy up to 100 {mu}J are focused to intensities ranging from 10{sup 13} to 10{sup 17} W/cm{sup 2}. We investigate the absorption and temporal evolution of the sample under irradiation by use of XUV spectroscopy. We discuss the origin of saturable absorption, radiative decay, bremsstrahlung and ionic line emission. Our experimental results are in good agreement with hydrodynamic simulations.

  19. A study on the laser welding of aluminum for end-capping of KMRR fuel elements

    International Nuclear Information System (INIS)

    The selecting of proper welding process for aluminum end-capping of KMRR nuclear fuel elements is considered important in respect to the soundness of weldments and the improvement of the performance of nuclear fuels during the operation in reactor. The probability of leakage of the fission products is mostly apt to occur at the weldments, and it is connected directly with the safety and life prediction of the nuclear reactor in operation. This study is to investigate the influence of Ti and Zr micro-additions on the grain refinement in Al weld metal and to prevent weld cracks in pure Al. In addition, mechanical properties of laser welded specimen were observed and the technical data for KMRR nuclear fuels manufacturing was provided. In the future, this study will also present the improvement of KMRR nuclear end-caps welding. (Author)

  20. Case study on the ultrafast laser ablation of thin aluminum films: dependence on laser parameters and film thickness

    Science.gov (United States)

    Olbrich, M.; Punzel, E.; Roesch, R.; Oettking, R.; Muhsin, B.; Hoppe, H.; Horn, A.

    2016-03-01

    Laser ablation using ultra-short pulsed laser radiation allows the removing of thin films with very high spatial resolution, and working with high repetition rate as well with high through-put. The ultrafast ablation of thin films of aluminum on float glass is investigated using focused femtosecond laser radiation ( λ = 1028 nm, t H = 200 fs, sech2, p f = 1 MHz) as function of the number of pulses N p per point (1-10) and the film thickness d (30-300 nm). It is observed that two thresholds are derived simultaneously for thin films with a thickness thicker than 100 nm by irradiating the metal with single pulsed laser radiation exhibiting a Gaussian intensity distribution: one threshold for gentle ablation H thr,gentle and the other for strong ablation H thr,strong. Multi-pulse irradiation varying the number of pulses per point identifies the incubation effect described by Jee et al. (J Opt Soc Am B 5(3):648, 1968). This model was applied on the thresholds for gentle and strong ablation. Also, varying the layer thickness reducing the thresholds for thin films due heat accumulation. To quantify the experimental data, numerical simulations solving the coupled heat transfer equation of the two-temperature model were performed. A new approach including the temperature dependence of the reflectivity is presented based on the model proposed by Brückner et al. (J Appl Phys 66:1326, 1989). The results of the simulation fit qualitative well to the experimental data of gentle ablation. Theoretical investigation for double pulses with a variable pulse separation time of 1-300 ps were performed in comparison with a single pulse.

  1. Laser-generated Macroscopic and Microscopic Surface Structures for the Joining of Aluminum and Thermoplastics using Friction Press Joining

    Science.gov (United States)

    Fuchs, Alexander N.; Wirth, Franz X.; Rinck, Philipp; Zaeh, Michael F.

    Structural lightweight construction is increasingly utilized in the aerospace and automotive industry. Hybrid structures have great potential, especially with regard to load-specific component layouts. Usually, a surface pre-treatment is applied prior to joining dissimilar materials to improve bonding mechanisms such as form closure. In previous studies pulsed wave (pw) lasers were used for structuring metals. This paper presents the results of aluminum pre-treatment via a continuous wave (cw) single-mode fiber laser: macroscopic and microscopic structures were generated on the aluminum surface; the samples were joined with glass fiber reinforced polyamide using Friction Press Joining (FPJ), a method for joining metals and thermoplastic polymers in lap joint configuration. Using these new methods for surface structuring, shear strength was increased by 40% compared to previous studies with pw lasers.

  2. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

  3. In Vitro Laser Ablation of Natural Marine Biofilms

    OpenAIRE

    Nandakumar, Kanavillil; Obika, Hideki; Utsumi, Akihiro; Ooie, Toshihiko; Yano, Tetsuo

    2004-01-01

    We studied the efficiency of pulsed low-power laser irradiation of 532 nm from an Nd:YAG (neodymium-doped yttrium-aluminum-garnet) laser to remove marine biofilm developed on titanium and glass coupons. Natural biofilms with thicknesses of 79.4 ± 27.8 μm (titanium) and 107.4 ± 28.5 μm (glass) were completely disrupted by 30 s of laser irradiation (fluence, 0.1 J/cm2). Laser irradiation significantly reduced the number of diatoms and bacteria in the biofilm (paired t test; P < 0.05). The remov...

  4. Thin-rod Yb:YAG regenerative laser amplifier

    Science.gov (United States)

    Maruko, A.; Nishio, M.; Matsubara, S.; Tanaka, M.; Takama, M.; Yoshida, T.; Kyomoto, K.; Okunishi, H.; Kato, K.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

    2014-09-01

    High-average-power, high-repetition-rates picosecond-pulsed regenerative ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser amplifiers were developed. The architecture used in the amplifiers, which are named as thin-rod, has a unique cooling scheme like slab lasers and also has a unique pumping scheme like photonic crystal fiber lasers, is suitable for high-average power Ytterbium lasers. This architecture also has high gain characteristics which is appropriate for the regenerative spectral and pulse shaping on high-repetition-rate, ultrashort-pulse amplifications.

  5. Two-garnet rodingite from Amador County, California

    Science.gov (United States)

    Duffield, W.A.; Beeson, M.H.

    1973-01-01

    Two distinct phases of garnet have been discovered in rodingite from Amador County, Calif. The two garnets are hydrogrossular and (hydro?) grossular-andradite. Only one, generally hydrogrossular, has been reported in rodingitcs studied by other workers. The rodingite of this study formed from a mafic dike with abundant euhedral plagioclase laths. The hydrogrossular is concentrated within the areas of these laths and is volumetrically about as abundant. The (hydro?) grossular-andradite is concentrated in the groundmass and as incursions into the plagioclase laths. The garnets apparently grew during one general episode of metasomatism, and their spatial distribution and compositions were controlled principally by the unequal distribution of iron and aluminum caused by the presence of plagioclase laths (and mafic minerals?) in the original unaltered dike.

  6. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a...... variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities with...

  7. Microstructure Characterization of Laser-Welded Nb-Microalloyed Silicon-Aluminum TRIP Steel

    Science.gov (United States)

    Grajcar, A.; Różański, M.; Stano, S.; Kowalski, A.

    2014-09-01

    This work presents the results of a microstructural characterization of welds in Nb-microalloyed TRIP steel with silicon partially replaced by aluminum. Tests of laser welding of thermomechanically processed sheet samples were carried out using keyhole welding and a solid-state laser. Welding penetration tests were conducted for heat input values between 0.037 and 0.048 kJ/mm. Identification of different microstructural constituents was carried out using light microscopy and scanning electron microscopy in the fusion zone (FZ), heat-affected zone (HAZ), and base metal. Special focus was put on the effect of cooling conditions on the stabilization of retained austenite in different zones. The intercritical, fine-grained, and coarse-grained regions of the HAZ were identified. It was determined that enriching austenite with carbon in the intercritical HAZ stabilizes this phase at a level close to the base metal, i.e., a 15% volume fraction. Despite a high cooling rate in the FZ and HAZ, interlath retained austenite is also present in these zones. The research involved microhardness measurements and characterizing non-metallic inclusions formed in the fusion zone. A good correlation between microstructures formed in different weld regions and microhardness results was obtained.

  8. Modeling the effect of laser heating on the strength and failure of 7075-T6 aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Florando, J.N., E-mail: florando1@llnl.gov; Margraf, J.D.; Reus, J.F.; Anderson, A.T.; McCallen, R.C.; LeBlanc, M.M.; Stanley, J.R.; Rubenchik, A.M.; Wu, S.S.; Lowdermilk, W.H.

    2015-07-29

    The effect of rapid laser heating on the response of 7075-T6 aluminum has been characterized using 3-D digital image correlation and a series of thermocouples. The experimental results indicate that as the samples are held under a constant load, the heating from the laser profile causes non-uniform temperature and strain fields, and the strain-rate increases dramatically as the sample nears failure. Simulations have been conducted using the LLNL multi-physics code ALE3D, and compared to the experiments. The strength and failure of the material was modeled using the Johnson–Cook strength and damage models. In order to capture the response, a dual-condition criterion was utilized which calibrated one set of parameters to low temperature quasi-static strain rate data, while the other parameter set is calibrated to high temperature high strain rate data. The thermal effects were captured using temperature dependent thermal constants and invoking thermal transport with conduction, convection, and thermal radiation.

  9. Efficacy of Holmium Laser Urethrotomy in Combination with Intralesional Triamcinolone in the Treatment of Anterior Urethral Stricture

    OpenAIRE

    Kumar, Santosh; Kapoor, Ankur; Ganesamoni, Raguram; Nanjappa, Bhuvanesh; Sharma, Varun; Uttam K Mete

    2012-01-01

    Purpose To evaluate the outcome of visual internal urethrotomy with a holmium:yttrium-aluminum-garnet laser along with intralesional triamcinolone injection. Materials and Methods Patients with an anterior urethral stricture less than 3 cm in length were evaluated by clinical history, physical examination, uroflowmetry, and retrograde urethrogram preoperatively. All patients were treated with holmium laser urethrotomy and intralesional triamcinolone (80 mg) injection under general or regional...

  10. Effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 1.2 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto a water-immersed type aluminum samples. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the higher the pulse density the larger the zone size with compressive residual stress. Densities of 900, 1350 and 2500 pulses/cm2 with infrared (1064 nm) radiation are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. Fatigue crack growth rate is compared in specimens with and without LSP process. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness in the 6061-T6 aluminum alloy

  11. Effect of an absorbent overlay on the residual stress field induced by laser shock processing on aluminum samples

    International Nuclear Information System (INIS)

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm2 with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy

  12. DEFORMATION SUBSTRUCTURES AND THEIR TRANSITIONS IN LASER SHOCK-COMPRESSED COPPER-ALUMINUM ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, M A; Schneider, M S; Jarmakani, H; Kad, B; Remington, B A; Kalantar, D H; McNaney, J; Cao, B; Wark, J

    2007-10-17

    It is shown that the short pulse durations (0.1-10 ns) in laser shock compression ensure a rapid decay of the pulse and quenching of the shocked sample in times that are orders of magnitude lower than in conventional explosively driven plate impact experiments. Thus, laser compression, by virtue of a much more rapid cooling, enables the retention of a deformation structure closer to the one existing during shock. The smaller pulse length also decreases the propensity for localization. Copper and copper aluminum (2 and 6 wt% Al) with orientations [001] and [{bar 1}34] were subjected to high intensity laser pulses with energy levels of 70 to 300 J delivered in an initial pulse duration of approximately 3 ns. The [001] and [{bar 1}34] orientations were chosen since they respectively maximize and minimize the number of slip systems with highest resolved shear stresses. Systematic differences of the defect substructure were observed as a function of pressure, stacking-fault energy and crystalline orientation. The changes in the mechanical properties for each condition were compared using micro- and nano-hardness measurements and correlated well with observations of the defect substructure. Three regimes of plastic deformation were identified and their transitions modeled: dislocation cells, stacking-faults, and twins. An existing constitutive description of the slip to twinning transition, based on the critical shear stress, was expanded to incorporate the effect of stacking-fault energy. A new physically-based criterion accounting for stacking-fault energy was developed that describes the transition from perfect loop to partial loop homogeneous nucleation, and consequently from cells to stacking-faults. These calculations predict transitions that are in qualitative agreement with the effect of SFE.

  13. Aluminum-Free Semiconductors and Packaging

    International Nuclear Information System (INIS)

    The use of laser diodes instead of flashlamps to pump solid state lasers generally results in lighter weight, more compact systems with improved efficiency and reliability. These traits are important to a wide variety of applications in military, industrial and other areas. Common solid state laser systems such as yttrium aluminum garnet doped with neodymium or ytterbium (Nd:YAG and Yb:YAG, respectively) require pump light in the 800 to 1000 nm range, and such laser diodes have typically been fabricated in the AlGaAs material system on a GaAs substrate. Unfortunately, the presence of aluminum in or near the light-generating regions of these devices appears to limit their high-power performance, so for improved performance attention has turned to the aluminum-free (''Al-free'') material system of InGaAsP on a GaAs substrate. Laser diodes in this system offer the wavelength coverage similar to the AlGaAs/GaAs material system, and early results suggest that they may offer improved high-power performance. However, such Al-free diodes are more challenging to manufacture than AlGaAs-based devices. The goal of this LDRD project has been to evaluate Al-free diode technology in comparison with conventional AlGaAs-based structures for use in diode-pumped solid state lasers. This has been done by testing commercially available devices, surveying the literature, developing in-house capability in order to explore new device designs, and by engaging a leading university research group in the field

  14. Aluminum-Free Semiconductors and Packaging

    Energy Technology Data Exchange (ETDEWEB)

    Emanuel, M.A.

    2000-02-03

    The use of laser diodes instead of flashlamps to pump solid state lasers generally results in lighter weight, more compact systems with improved efficiency and reliability. These traits are important to a wide variety of applications in military, industrial and other areas. Common solid state laser systems such as yttrium aluminum garnet doped with neodymium or ytterbium (Nd:YAG and Yb:YAG, respectively) require pump light in the 800 to 1000 nm range, and such laser diodes have typically been fabricated in the AlGaAs material system on a GaAs substrate. Unfortunately, the presence of aluminum in or near the light-generating regions of these devices appears to limit their high-power performance, so for improved performance attention has turned to the aluminum-free (''Al-free'') material system of InGaAsP on a GaAs substrate. Laser diodes in this system offer the wavelength coverage similar to the AlGaAs/GaAs material system, and early results suggest that they may offer improved high-power performance. However, such Al-free diodes are more challenging to manufacture than AlGaAs-based devices. The goal of this LDRD project has been to evaluate Al-free diode technology in comparison with conventional AlGaAs-based structures for use in diode-pumped solid state lasers. This has been done by testing commercially available devices, surveying the literature, developing in-house capability in order to explore new device designs, and by engaging a leading university research group in the field.

  15. Approach for determination of detonation performance and aluminum percentage of aluminized-based explosives by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Rezaei, Amir Hossein; Keshavarz, Mohammad Hossein; Tehrani, Masoud Kavosh; Reza Darbani, Seyyed Mohammad; Farhadian, Amir Hossein; Mousavi, Seyyed Jabbar; Mousaviazar, Ali

    2016-04-20

    Energetic materials containing aluminum powder are hazardous compounds, which have wide applications as propellants, explosives, and pyrotechnics. This work introduces a new method on the basis of the laser-induced breakdown spectroscopy technique in air and argon atmospheres to investigate determination of aluminum content and detonation performance of 1,3,5-trinitro-1,3,5-triazine (RDX)-based aluminized explosives. Plasma emission of aluminized RDX explosives are recorded where atomic lines of Al, C, H, N, and O, as well as molecular bands of AlO and CN are identified. The formation mechanism of AlO and CN molecular bands is affected by the aluminum percentage and oxygen content present in the composition and plasma. Relative intensity of the Al/O is used to determine detonation velocity and pressure of the RDX/Al samples. The released energy in the laser-induced plasma of aluminized RDX composition is related to the heat of explosion and percentage of aluminum. PMID:27140093

  16. Characteristics of the aluminum alloy plasma produced by a 1064 nm Nd:YAG laser with different irradiances

    Indian Academy of Sciences (India)

    W F Luo; X X Zhao; Q B Sun; C X Gao; J Tang; H J Wang; W Zhao

    2010-06-01

    The plasma generated by 1064 nm Nd:YAG laser irradiation of aluminum alloy in air at atmospheric pressure was studied spectroscopically. The electron density inferred by measuring the Stark-broadened line profile of Si(I) 288.16 nm decreases with increasing distance from the target surface. The electron temperature was determined using the Boltzmann plot method with nine strong neutral aluminum lines. Due to the thermal conduction towards the solid target and radiative cooling of the plasma as well as conversion of thermal energy into kinetic energy, the electron temperature decreases both at the plasma edge and close to the target surface. Electron density and electron temperature were also studied as functions of laser power density. At the same time, the validity of the assumption of local thermodynamic equilibrium and the effect of self-absorption were discussed in light of the results obtained.

  17. Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

    DEFF Research Database (Denmark)

    Bodea, M. A.; Sbarcea, G.; Naik, G. V.; Boltasseva, Alexandra; Klar, T. A.; Pedarnig, J. D.

    2013-01-01

    Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass...... from dense and small-grained ceramic targets show optical transmission larger than 70 % in the visible and reveal an onset of metallic reflectivity in the near infrared at 1100 nm and a crossover to a negative real part of the permittivity at approximately 1500 nm. In comparison to noble metals, doped...

  18. Recession velocity of ablated surface for LY-12 aluminum targets irradiated by a long-pulse laser beam

    International Nuclear Information System (INIS)

    A method used to measure the burnthrough time of LY-12 aluminum targets irradiated by a 1.06 μm free-oscillation long-pulse laser beam is described. Measurement techniques for ablated target parameters Δm and h with electronic balance, metallograph and collector are also presented. The recession velocity and ablation velocity of targets have been experimentally obtained. For laser power I = 105 ∼ 107 W/cm2, the recession velocity ranges from 0.5 m/s to 3.8 m/s, and the ablation velocity between 1 g/s and 8 g/s

  19. Multi-stage pulsed laser deposition of aluminum nitride at different temperatures

    Science.gov (United States)

    Duta, L.; Stan, G. E.; Stroescu, H.; Gartner, M.; Anastasescu, M.; Fogarassy, Zs.; Mihailescu, N.; Szekeres, A.; Bakalova, S.; Mihailescu, I. N.

    2016-06-01

    We report on multi-stage pulsed laser deposition of aluminum nitride (AlN) on Si (1 0 0) wafers, at different temperatures. The first stage of deposition was carried out at 800 °C, the optimum temperature for AlN crystallization. In the second stage, the deposition was conducted at lower temperatures (room temperature, 350 °C or 450 °C), in ambient Nitrogen, at 0.1 Pa. The synthesized structures were analyzed by grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy and spectroscopic ellipsometry (SE). GIXRD measurements indicated that the two-stage deposited AlN samples exhibited a randomly oriented wurtzite structure with nanosized crystallites. The peaks were shifted to larger angles, indicative for smaller inter-planar distances. Remarkably, TEM images demonstrated that the high-temperature AlN "seed" layers (800 °C) promoted the growth of poly-crystalline AlN structures at lower deposition temperatures. When increasing the deposition temperature, the surface roughness of the samples exhibited values in the range of 0.4-2.3 nm. SE analyses showed structures which yield band gap values within the range of 4.0-5.7 eV. A correlation between the results of single- and multi-stage AlN depositions was observed.

  20. Dissimilar joining of galvanized high-strength steel to aluminum alloy in a zero-gap lap joint configuration by two-pass laser welding

    International Nuclear Information System (INIS)

    Highlights: • Defect-free two-pass laser partially penetrated lap joint of galvanized steel to aluminum was achieved. • The thickness of the Al-rich intermetallic compounds could be controlled by optimal parameters. • The dynamic behavior of the molten pool and keyhole were monitored by a high speed charge-coupled device camera. • The presence of zinc in the intermetallic compounds could improve the strength of the lap joints. - Abstract: A welding procedure based on using two-pass laser scans is introduced for dissimilar joining of overlapped galvanized high-strength dual-phase (DP) steel DP590 to aluminum alloy (AA) 6061 sheets. The first pass is based on a defocused laser spot that scans across the top of the two overlapped sheets and heats the zinc coating at the faying surface to be melted and partially vaporized, while the second pass is executed with a focused laser spot in order to perform the welding. Completely defect-free galvanized steel to aluminum lap joints were obtained by using this two-pass laser welding procedure. An on-line machine vision system was applied to monitor the keyhole dynamics during the laser welding process. An energy-dispersive X-ray spectroscopy (EDS) was carried out to determine the atomic percent of zinc, aluminum, and iron in the galvanized steel to aluminum lap joints. Mechanical testing and micro-hardness test were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the lap joint of galvanized steel to aluminum obtained by the two-pass laser welding approach had a higher failure value than those joints obtained when the zinc at the faying surface was mechanically removed under the same welding speed and laser power

  1. Morphology and characteristics of laser-induced aluminum plasma in argon and in air: A comparative study

    Science.gov (United States)

    Bai, Xueshi; Cao, Fan; Motto-Ros, Vincent; Ma, Qianli; Chen, Yanping; Yu, Jin

    2015-11-01

    In laser-induced breakdown spectroscopy (LIBS), ablation takes place in general in an ambient gas of the atmospheric pressure, often in air but also in noble gas such as argon or helium. The use of noble gas is known to significantly improve the performance of the technique. We investigate in this work the morphology and the characteristics of induced plasma in argon and in air. The purpose is to understand the mechanism of the analytical performance improvement by the use of argon ambient with respective to air ambient and the dependence on the other experimental parameters such as the laser fluence. The observation of plasma morphology in different ambient gases provides also information for better design of the detection system which optimizes the signal collection according to the used ambient gases. More specifically, the expansion of the plasma induced on an aluminum target with nanosecond infrared (1064 nm) laser pulse in two ambient gases, argon and the atmospheric air, has been studied with spectroscopic imaging at short delays and with emission spectroscopy at longer delays. With relatively low ablation laser fluence (65 J/cm2), similar morphologies have been observed in argon and in air over the early stage of plasma expansion, while diagnostics at longer delay shows stronger emission, higher electron density and temperature for plasma induced in argon. With higher ablation laser fluence (160 J/cm2) however, different expansion behaviors have been observed, with a stagnating aluminum vapor near the target surface in air while a propagating plume away from the target in argon. The craters left on the target surface show as well corresponding difference: in air, the crater is very shallow with a target surface chaotically affected by the laser pulse, indicating an effective re-deposition of the ablated material back to the crater; while in Ar a deeper crater is observed, indicating an efficient mass removal by laser ablation. At longer delays, a brighter

  2. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the Hα line profiles and Thomson scattering spectra

    International Nuclear Information System (INIS)

    We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the Hα, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the Hα full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium

  3. Electrode patterning and annealing processes of aluminum-doped zinc oxide thin films using a UV laser system

    Science.gov (United States)

    Hsiao, Wen-Tse; Tseng, Shih-Feng; Huang, Kuo-Cheng; Chiang, Donyau

    2013-01-01

    This study presents the hybrid processing (patterning and annealing) of aluminum-doped zinc oxide (AZO) films in a one-step process using a diode-pumped-solid-state (DPSS) ultraviolet (UV) laser system. The focused laser beam had a diameter of 30 μm and the positive defocused laser beam had a diameter of 1 mm. Both beams were adjusted using a UV laser-processing system. AZO films were deposited on Corning Eagle 2000® optical glass sheets with a thickness of 0.7 mm using a sputtering method. The deposited films were approximately 200 nm. The optoelectronic properties of machined (patterning and annealing) AZO films depend on the laser pulse frequency and galvanometer scanning speed. The surface morphology, roughness, optical transmittance, and resistivity of the films after the laser patterning and annealing processes were measured using a three-dimensional confocal laser scanning microscope, a field emission scanning electron microscope (FE-SEM), a spectrophotometer, and a four-point probe instrument, respectively. Experimental results indicate that the ablation depth increased as the pulse repetition frequency increased. The ablation depth also decreased as the galvanometric scanning speed increased. The transmittance spectra of the film changes slightly after laser annealing, and the average transmittance in the visible region is approximately 83%. All resistivity values of laser-patterned and annealed AZO films decreased significantly. The structural properties grain size was calculated firm the X-ray diffraction (XRD) spectra using the Scherrer equation that increased from 7.4 nm to 12 nm as the annealing scanning speed decreased from 800 mm/s to 400 mm/s. The root mean square (RMS) values of annealed AZO films treated with a laser scanning speed of 500 mm/s with a pulse repetition frequency of 40 kHz, 55 kHz, and 70 kHz were 1.1 nm, 1.2 nm, and 1.8 nm, respectively.

  4. Ten-years experience of laser use in aesthetic surgery

    Science.gov (United States)

    Gulev, Valerii S.; Dobrjakova, Olga B.; Dobrjakov, Boris S.

    2001-10-01

    A collaboration of the laser physicist and aesthetic surgeons has started 10 years ago. Within the period 1992 - 2000 we have carried out the investigation of the influence of the pulsed radiation, emitted by lasers having as active mediums crystals of the aluminum-yttrium garnet and alexandrite, on the cultures of the alive tissue and the fibrosis capsules around foreign bodies in the animals. Besides, we have studied the clinical protocol: in majority, patients were women after mammary augmentation. The laser tatoo non-invasive removals were marked at the beginning of the pulse of the Q-switch neodymium yttrium-aluminum garnet laser radiation used in human. It was obtained that this laser radiation broke the cell proliferation without any mutations and morphology changes. It was also noticed much evidence that the high functional fibroblast activities were registered in fibrosis capsules of not exposed animals to the laser radiation. It was also noticed that the use of laser radiation affected the speed and quality of the productive inflammation. The softening of the fibrous capsule around the mammary implant and the reduction of the pronounced rubbers were the clinical effects of the laser radiation.

  5. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Napolitani, E. [MATIS IMM-CNR at Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Impellizzeri, G. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Giarola, M. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); De Salvador, D. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Privitera, V.; Priolo, F. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Mariotto, G. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); Carnera, A. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-31

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm{sup −1}, due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm{sup −1}, which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm{sup −1} is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm{sup −1}.

  6. In Vitro Guidance of Dental Pulp Cells by Nd:YAG Laser-Irradiated Endothelial Cells

    OpenAIRE

    Masuda, Yoshiko Murakami; Yamada, Yoshishige; Kimura, Yuichi

    2012-01-01

    Objective: After endothelial cells were ablated by neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation, we investigated the response of pulp cells by examining the expression of transforming growth factor beta-1 (TGF-β1). Background data: The reaction of stimulated blood vessels is related to the initiation of dentinogenesis. After artificial injury of endothelial cells, pulp cells migrate to the site of the injured endothelial cells. Materials and methods: Rat aortic endothelial cel...

  7. Underwater YAG laser welding technique

    International Nuclear Information System (INIS)

    When planning preventive maintenance of reactor components using welding, it is necessary to consider special environments such as narrow space or difficult accessibility while minimizing exposure to radiation in the reactor pressure vessel. Toshiba has developed an underwater neodymium: yttrium-aluminum-garnet (Nd: YAG) laser welding technique. The features of this welding technique are low-heat-input welding and compact welding machine dimensions for welding in narrow spaces. This paper provides a summary of the new welding technique as a reliable welding technology. (author)

  8. Tribological properties of laser cladding TiB2 particles reinforced Ni-base alloy composite coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Long He; Ye-Fa Tan; Xiao-Long Wang; Qi-Feng Jing; Xiang Hong

    2015-01-01

    To improve the wear resistance of aluminum alloy frictional parts,TiB2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding.The microstructure and tribological properties of the composite coatings were investigated.The results show that the composite coating contains the phases of NiAl,Ni3Al,Al3Ni2,TiB2,TiB,TiC,CrB,and Cr23C6.Its microhardness is HV0.5 855.8,which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy.The friction coefficients of the composite coatings are reduced by 6.8 %-21.6 % and 13.2 %-32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys,while the wear losses are 27.4 %-43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %-32.7 % of those of the aluminum alloys at different loads.At the light loads ranging from 3 to 6 N,the calculated maximum contact stress is smaller than the elastic limit contact stress.The wear mechanism of the composite coatings is micro-cutting wear,but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress.As the loads increase to 12 N,the calculated flash temperature rises to 332.1 ℃.The composite coating experiences multi-plastic deformation wear,micro-brittle fracture wear,and oxidative wear.

  9. Optical and structural properties of Pr.sup.3+./sup. doped gadolinium gallium garnet GGG planar waveguides grown by pulsed-laser depositium

    Czech Academy of Sciences Publication Activity Database

    Lančok, Ján; Garapon, C.; Jelínek, Miroslav; Brenier, R.; Mugnier, J.

    Heraklion : IESL - FORTH, 2003 - (Fotakis, C.). WePS91 [COLA´03: International Conference on Laser Ablation /7./. 05.10.2003-10.10.2003, Kréta] Keywords : GGG * PLD * thin films * optical properties

  10. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments.

    Science.gov (United States)

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-12-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG. PMID:26719647

  11. Dynamics of a femtosecond/picosecond laser-induced aluminum plasma out of thermodynamic equilibrium in a nitrogen background gas

    International Nuclear Information System (INIS)

    Beyond the experimental studies, the assessment of the ability of ultra-short (femto or picosecond) laser pulses to provide correct estimates of the elemental composition of unknown samples using laser-induced breakdown spectroscopy requires the modeling of a typical situation. The present article deals with this modeling for aluminum in nitrogen. A spherical layer model is developed. The central aluminum plasma is produced by the ultra-short pulse. This plasma is described using our collisional–radiative model CoRaM-Al in an upgraded version involving 250 levels. Its expansion and relaxation take place in nitrogen, where the formation and the propagation of a shock wave are taken into account. In this shocked nitrogen layer, the equilibrium conditions are assumed. Mass, momentum and energy conservation equations written under an Eulerian form are used to correctly model the global dynamics. Energy losses are due to radiative recombination, thermal Bremsstrahlung and spontaneous emission. These elementary processes are implemented. The only input parameters are the pulse energy E0, the ablated mass M of the sample and the pressure p0 of the surrounding gas. The equilibrium composition involving N2, N, N2+, N+ and free electrons of the shocked nitrogen layer is calculated from the thermodynamic database of our collisional–radiative model CoRaM-N2. The conditions E0 = 10 mJ and M ≃ 10−10 kg corresponding to a 532 nm laser pulse are chosen. The model assumes the initial equilibrium of the aluminum plasma produced by the laser pulse absorbed by the sample. Then, owing to the significant overpressure with respect to the background gas (p0 is assumed atmospheric), the surrounding gas starts to be compressed while the propagation of a shock wave takes place. The shock layer maximum pressure is obtained at approximately 20 ns. At this characteristic time, the nitrogen pressure is around 400 times the atmospheric pressure. A shock velocity of 7 km s−1 is predicted

  12. Alkaline corrosion properties of laser-clad aluminum/titanium coatings

    DEFF Research Database (Denmark)

    Aggerbeck, Martin; Herbreteau, Alexis; Rombouts, Marleen;

    2015-01-01

    microscope, scanning electron microscope - energy-dispersive X-ray spectroscopy and X-Ray Diffraction, together with alkaline exposure tests and potentiodynamic measurements at pH 13.5. Findings - Cladding resulted in a heterogeneous solidification microstructure containing an aluminum matrix with...... supersaturated titanium ( (1 weight per cent), Al3Ti intermetallics and large partially undissolved Ti6Al4V particles. Heat treatment lowered the titanium concentration in the aluminum matrix, changed the shape of the Al3Ti precipitates and increased the degree of dissolution of the Ti6Al4V particles. Corrosion...... testing showed significant localized dissolution of the aluminum matrix. Research limitations/implications – Increased titanium concentration and heat treatment gave improved alkaline corrosion properties. At pH 13.5, the Al3Ti phases were protected, while the aluminum matrix corroded. Practical...

  13. Effect of laser shock processing on residual stress and fatigue behavior of 6061-T651 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    REN Xu-dong; ZHANG Yong-kang; ZHOU Jian-zhong; FEN Ai-xin

    2006-01-01

    Laser shock processing is a very new technique and an emerging modern process that generates compressive stresses much deeper into the surfaces of metals or alloys. A brief parametric study of the effect of laser parameters on fatigue behavior and residual stress state generated in 6061-T651 alloy specimens was summarized. Residual stress of 6061-T651 alloy was analyzed both before and after laser processing with multishocks. The material remains in compressive residual stress of approximate lmm in depth which is approximately 10 times deeper than that can be achieved with the conventional technique, and the maximal compressive residual stress at the surface of the sampleis about -350MPa. Near the surface, yield strength and hardness are found to be increased by the laser shock. The ratio of fatigue crack initiation life for the laser-shocked to unshocked specimens is found to be 4.9 for specimens. The results clearly show that LSP is an effective surface treatment technique for improving the fatigue performance of aluminum alloys.

  14. Energy conversion and momentum coupling of the sub-kJ laser ablation of aluminum in air atmosphere

    International Nuclear Information System (INIS)

    Energy conversion and momentum coupling using nano-second 1-μm-wavelength pulse laser irradiation on an aluminum target were measured in air and nitrogen gas atmospheres over a wide range of laser pulse energies from sub-J to sub-kJ. From the expansion rate of the shock wave, the blast-wave energy conversion efficiency, ηbw, was deduced as 0.59 ± 0.02 in the air atmosphere at an ambient pressure from 30 to 101 kPa for a constant laser fluence at 115 J/cm2. Moreover, the momentum coupling of a circular disk target was formulated uniquely as a function of the dimensionless shock-wave radius and the ratio of the laser spot radius to the disk radius, while ηbw could be approximated as constant for the laser fluence from 4.7 to 4.1 kJ/cm2, and the ambient pressure from 0.1 to 101 kPa

  15. Hybrid laser/arc welding of advanced high strength steel to aluminum alloy by using structural transition insert

    International Nuclear Information System (INIS)

    Highlights: • A concept welding procedure was presented for joining dissimilar alloys. • Controlling of temperature improved mechanical properties. • Microstructure analysis showed presence of tempered martensite. • Optimum stand-off distance caused stability of molten pool. - Abstract: The present investigation is related to the development of the welding procedure of the hybrid laser/arc welding (HLAW) in joining thick dissimilar materials. The HLAW was applied to join aluminum alloy (AA6061) to an advanced high strength steel (AHSS) where an explosively welded transition joint, TRICLAD®, was used as an intermediate structural insert between the thick plates of the aluminum alloy and AHSS. The welds were characterized by an optical microscope, scanning electron microscope (SEM), tensile test, charged coupled device (CCD) camera, and microhardness measurement. The groove angle was optimized for the welding process based on the allowed amount of heat input along the TRICLAD® interface generated by an explosive welding. The weld was fractured in the heat affected zone of the aluminum side in the tensile test. The microhardness was shown that the temperature variation caused minor softening in the heat affected zone satisfying the requirement that the width of the softened heat affected zone in the steel side falls within 15.9 mm far away from the weld centerline. The microstructure analysis showed the presence of tempered martensite at the vicinity of the weld area, which it was a cause of softening in the heat affected zone

  16. Ballistic phonon and thermal radiation transport across a minute vacuum gap in between aluminum and silicon thin films: Effect of laser repetitive pulses on transport characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.

    2016-08-01

    Short-pulse laser heating of aluminum and silicon thin films pair with presence of a minute vacuum gap in between them is considered and energy transfer across the thin films pair is predicted. The frequency dependent Boltzmann equation is used to predict the phonon intensity distribution along the films pair for three cycles of the repetitive short-pulse laser irradiation on the aluminum film surface. Since the gap size considered is within the Casimir limit, thermal radiation and ballistic phonon contributions to energy transfer across the vacuum gap is incorporated. The laser irradiated field is formulated in line with the Lambert's Beer law and it is considered as the volumetric source in the governing equations of energy transport. In order to assess the phonon intensity distribution in the films pair, equivalent equilibrium temperature is introduced. It is demonstrated that thermal separation of electron and lattice sub-systems in the aluminum film, due to the short-pulse laser irradiation, takes place and electron temperature remains high in the aluminum film while equivalent equilibrium temperature for phonons decays sharply in the close region of the aluminum film interface. This behavior is attributed to the phonon boundary scattering at the interface and the ballistic phonon transfer to the silicon film across the vacuum gap. Energy transfer due to the ballistic phonon contribution is significantly higher than that of the thermal radiation across the vacuum gap.

  17. Study on the effect of welding current during laser beam-resistance seam welding of aluminum alloy 5052

    Institute of Scientific and Technical Information of China (English)

    Li Yongqiang; Zhao Xihua; Zhao He; Cao Haipeng; Zhao Huanling

    2008-01-01

    The effect of welding current on the weld shape and tensile shear load during laser beam-resistance seam welding (LB-RSW) of aluminum alloy 5052 is studied. Experimental results show that the penetration depth, weld width,tensile shear load and the ratio of penetration depth to weld width of LB-RSW are bigger than those of laser beam welding(LBW) under the same conditions and the former three parameters increase as welding current rises. The weld shape of LB-RSW below 5 kA welding current is nearly the same as that of LBW. The weld morphology is protuberant under the condition of 5 kA welding current and 0.8 m/min welding speed. Furthermore, the microstructure of the weld seam of LB-RSW is coarser than that of LBW.

  18. Influence of neodymium-doping on structure and properties of yttrium aluminium garnet

    DEFF Research Database (Denmark)

    Zhang, X.D.; He, W.; Yue, Yuanzheng;

    2013-01-01

    We study the impact of the Nd-doping on the grain formation, the crystal structure, and the fluorescence of the Yttrium Aluminum Garnet (YAG). The results show that Nd-doping leads to the YAG lattice expansion and distortion, and hence to an increase in defect concentration. This is attributed to...

  19. Dynamics of a femtosecond/picosecond laser-induced aluminum plasma out of thermodynamic equilibrium in a nitrogen background gas

    Science.gov (United States)

    Morel, Vincent; Bultel, Arnaud; Annaloro, Julien; Chambrelan, Cédric; Edouard, Guillaume; Grisolia, Christian

    2015-01-01

    Beyond the experimental studies, the assessment of the ability of ultra-short (femto or picosecond) laser pulses to provide correct estimates of the elemental composition of unknown samples using laser-induced breakdown spectroscopy requires the modeling of a typical situation. The present article deals with this modeling for aluminum in nitrogen. A spherical layer model is developed. The central aluminum plasma is produced by the ultra-short pulse. This plasma is described using our collisional-radiative model CoRaM-Al in an upgraded version involving 250 levels. Its expansion and relaxation take place in nitrogen, where the formation and the propagation of a shock wave are taken into account. In this shocked nitrogen layer, the equilibrium conditions are assumed. Mass, momentum and energy conservation equations written under an Eulerian form are used to correctly model the global dynamics. Energy losses are due to radiative recombination, thermal Bremsstrahlung and spontaneous emission. These elementary processes are implemented. The only input parameters are the pulse energy E0, the ablated mass M of the sample and the pressure p0 of the surrounding gas. The equilibrium composition involving N2, N, N2+, N+ and free electrons of the shocked nitrogen layer is calculated from the thermodynamic database of our collisional-radiative model CoRaM-N2. The conditions E0 = 10 mJ and M ≃ 10- 10 kg corresponding to a 532 nm laser pulse are chosen. The model assumes the initial equilibrium of the aluminum plasma produced by the laser pulse absorbed by the sample. Then, owing to the significant overpressure with respect to the background gas (p0 is assumed atmospheric), the surrounding gas starts to be compressed while the propagation of a shock wave takes place. The shock layer maximum pressure is obtained at approximately 20 ns. At this characteristic time, the nitrogen pressure is around 400 times the atmospheric pressure. A shock velocity of 7 km s- 1 is predicted. The

  20. Laser lithotripsy of a urethral calculus via ischial urethrotomy in a steer.

    Science.gov (United States)

    Streeter, R N; Washburn, K E; Higbee, R G; Bartels, K E

    2001-09-01

    A steer examined because of obstructive urolithiasis and urethral rupture underwent laser lithotripsy, using a chromium-thulium-holmium:yttrium-aluminum-garnet (Ho:YAG) laser inserted through an ischial urethrotomy. Procedures were performed with caudal epidural anesthesia. Six months after surgery, the urethra was patent with no clinical evidence of urethral stricture or fistula. Ischial urethrotomy provided rapid access to the bladder for catheterization and to the obstructive urolith for lithotripsy. Laser lithotripsy was a rapid and effective means of urolith removal in this steer. PMID:11549094

  1. Gas dynamic effects on formation of carbon dimers in laser-produced plasmas

    Science.gov (United States)

    Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.

    2011-09-01

    We investigated the effect of helium and nitrogen pressures on the dynamics of molecular species formation during laser ablation of carbon. For producing plasmas, planar carbon targets were irradiated with 1064 nm, 6 ns pulses from an Nd:yttrium aluminum garnet laser. The emission from excited C2 and CN molecules was studied using space resolved optical time-of-flight emission spectroscopy and spectrally resolved fast imaging. The intensity oscillations in C2 and CN monochromatic fast imaging and their emission space-time contours suggest that recombination is the major mechanism of C2 formation within the laser ablation carbon plumes in the presence of ambient gas.

  2. Local thermodynamic equilibrium and related metrological issues involving collisional-radiative model in laser-induced aluminum plasmas

    Science.gov (United States)

    Travaillé, G.; Peyrusse, O.; Bousquet, B.; Canioni, L.; Pierres, K. Michel-Le; Roy, S.

    2009-10-01

    We present a collisional-radiative approach of the theoretical analysis of laser-induced breakdown spectroscopy (LIBS) plasmas. This model, which relies on an optimized effective potential atomic structure code, was used to simulate a pure aluminum plasma. The description of aluminum involved a set of 220 atomic levels representative of three different stages of ionization (Al 0, Al + and Al ++). The calculations were carried for stationary plasmas, with input parameters ( ne and Te) ranging respectively between 10 13-18 cm - 3 and 0.3-2 eV. A comparison of our atomic data with some existing databases is made. The code was mainly developed to address the validity of the local thermodynamic equilibrium (LTE) assumption. For usual LIBS plasma parameters, we did not reveal a sizeable discrepancy of the radiative equilibrium of the plasma towards LTE. For cases where LTE was firmly believed to stand, the Boltzmann plot outputs of this code were used to check the physical accuracy of the Boltzmann temperature, as it is currently exploited in several calibration-free laser-induced breakdown spectroscopy (CF-LIBS) studies. In this paper, a deviation ranging between 10 and 30% of the measured Boltzmann temperature to the real excitation temperature is reported. This may be due to the huge dispersion induced on the line emissivities, on which the Boltzmann plots are based to extract this parameter. Consequences of this fact on the CF-LIBS procedure are discussed and further insights to be considered for the future are introduced.

  3. Local thermodynamic equilibrium and related metrological issues involving collisional-radiative model in laser-induced aluminum plasmas

    International Nuclear Information System (INIS)

    We present a collisional-radiative approach of the theoretical analysis of laser-induced breakdown spectroscopy (LIBS) plasmas. This model, which relies on an optimized effective potential atomic structure code, was used to simulate a pure aluminum plasma. The description of aluminum involved a set of 220 atomic levels representative of three different stages of ionization (Al0, Al+ and Al++). The calculations were carried for stationary plasmas, with input parameters (ne and Te) ranging respectively between 1013-18 cm-3 and 0.3-2 eV. A comparison of our atomic data with some existing databases is made. The code was mainly developed to address the validity of the local thermodynamic equilibrium (LTE) assumption. For usual LIBS plasma parameters, we did not reveal a sizeable discrepancy of the radiative equilibrium of the plasma towards LTE. For cases where LTE was firmly believed to stand, the Boltzmann plot outputs of this code were used to check the physical accuracy of the Boltzmann temperature, as it is currently exploited in several calibration-free laser-induced breakdown spectroscopy (CF-LIBS) studies. In this paper, a deviation ranging between 10 and 30% of the measured Boltzmann temperature to the real excitation temperature is reported. This may be due to the huge dispersion induced on the line emissivities, on which the Boltzmann plots are based to extract this parameter. Consequences of this fact on the CF-LIBS procedure are discussed and further insights to be considered for the future are introduced.

  4. Laser-induced spallation of aluminum and Al alloys at strain rates above 2x106 s-1

    International Nuclear Information System (INIS)

    Material microstructure is a significant determinant of the tensile stress at which materials fail. Using a high-energy laser to drive shocks in thin slabs, we have explored the role material microstructure plays on the spall strength of high-purity and alloyed aluminum at strain rates of (2-7.5)x106 s-1. Slabs of pure recrystallized Al and recrystallized or cold worked Al+3 wt % Mg were shock driven using the Z-Beamlet Laser at Sandia National Laboratories. Velocity interferometer measurements determined the spall strength of the materials, and postshot target analysis explored the microscopic fracture morphology. We observed the greatest spall strength for large-grained, recrystallized high-purity aluminum, with the dominant failure mode being ductile and transgranular. We observe for the first time at these strain rates fracture features for a fine-grained Al+3 wt % Mg that were a combination of brittle intergranular and ductile transgranular fracture types. Postshot analysis of target cross sections and hydrocode simulations indicate that this mixed-mode failure results from spall dynamics occurring on spatial scales on the order of the grain size. Differences in spall strength between these Al samples were experimentally significant and correlate with the damage morphologies observed

  5. Fluorescence losses from Yb:YAG slab lasers.

    Science.gov (United States)

    Chen, Ying; Rapaport, Alexandra; Chung, Te-yuan; Chen, Bin; Bass, Michael

    2003-12-20

    We report on the distribution of fluorescence that can be emitted through the surfaces of a ytterbium-doped yttrium aluminum garnet (Yb:YAG) slab-shaped high-power solid-state laser. Slab shapes considered include parallel or antiparallel Brewster endfaced slabs and rectangular parallelepiped slabs. We treat cases in which all the faces of these slabs are in air, or with water or another coating on the largest faces. The fraction of the fluorescence emitted through each face, its distribution over that face, and the directions in which it travels are shown to be important to the design of high-power slab lasers. PMID:14717292

  6. Effect of erbium, chromium: yttrium, scandium, gallium, garnet laser and casein phosphopeptide-amorphous calcium phosphate on surface micro-hardness of primary tooth enamel

    OpenAIRE

    Subramaniam, Priya; Pandey, Annu

    2014-01-01

    Objective: The aim was to evaluate the effect of Er, Cr: YSGG laser and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on surface micro-hardness of primary tooth enamel. Materials and Methods: A total of 30 freshly extracted caries free primary anterior teeth were cleaned and stored in 1% thymol. Teeth were embedded in acrylic resin such that only their buccal surfaces were exposed and were divided into four groups. Group I: Five intact teeth (negative control). The remaining 25 ...

  7. Dissimilar Laser Welding/Brazing of 5754 Aluminum Alloy to DP 980 Steel: Mechanical Properties and Interfacial Microstructure

    Science.gov (United States)

    Yang, Jin; Li, Yulong; Zhang, Hua; Guo, Wei; Weckman, David; Zhou, Norman

    2015-11-01

    A diode laser welding/brazing technique was used for lap joining of 5754 aluminum alloy to DP 980 steel with Al-Si filler metal. The correlation between joint interfacial microstructure, wettability of filler metal, and mechanical properties was systematically investigated. At low laser power (1.4 kW), a layer of intermetallic compounds, composed of θ-Fe(Al,Si)3 and τ 5 -Al7.2Fe1.8Si, was observed at the interface between fusion zone and steel. Because of the poor wettability of filler metal on the steel substrate, the joint strength was very low and the joint failed at the FZ/steel interface. When medium laser power (2.0 kW) was applied, the wettability of filler metal was enhanced, which improved the joint strength and led to FZ failure. With further increase of laser power to 2.6 kW, apart from θ and τ 5, a new hard and brittle η-Fe2(Al,Si)5 IMC with microcracks was generated at the FZ/steel interface. The formation of η significantly degraded the joint strength. The failure mode changed back to interfacial failure.

  8. Comparative Study of Two Methods of Orthogonal Double-Pulse Laser-Induced Breakdown Spectroscopy of Aluminum

    Science.gov (United States)

    Safi, A.; Bahreini, M.; Tavassoli, S. H.

    2016-03-01

    Double-pulse laser induced breakdown spectroscopy (DP-LIBS) of aluminum sample is studied experimentally in orthogonal configuration in air. In this configuration, two schemes of reheating and pre-ablation are examined and the results are compared with single pulse one. The effect of delay time between two laser pulses on emission line intensities of plasma is investigated. Some of the parameters that have been involved in different mechanism of signal enhancement such as plasma temperature, sample heating effects, atmospheric effects, and modification of the ablation dynamics are more discussed. Investigation of the effect of laser pulse energy on emission line intensities in single pulse LIBS experiment demonstrate that because of saturation effects the intensities will not increase necessarily by increasing the laser pulse energy. Moreover, the results show that the electron temperature and rate of mass removal in orthogonal configuration of DP-LIBS is higher than that of single pulse with the same total energy. It is suggested that for correct comparison between single and double pulse results, the optimum pulse energy in single pulse should be considered. Overall, our results demonstrate that under optimized conditions the signal enhancement is much more in pre-ablation configuration than re-heating configuration.

  9. Effect of laser parameters on arc behavior of laser-TIG double-side welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Miao Yugang; Li Liqun; Zhang Xinge; Chen Yanbin; Wu Lin

    2010-01-01

    The influence of laser parameters on arc behavior of laser-TIG double-side welding was investigated by utilizing CCD sensor and image processing methods. It was found that arc images had an obvious transformation from laser preheating to laser plasma ejected from the keyhole bottom, resulting in the phenomena of arc column convergence and arc root constriction. The attraction phenomenon of the laser and the arc is also found in laser-TIG double-side welding. More noteworthy is that the behavior of arc attraction or constriction became much obvious at a lower current or laser plasma ejected from the keyhole bottom. The decrease in arc voltage had a certain relation with the improvement of arc stability.

  10. Recycling stainless steel orthodontic brackets with Er:YAG laser – An environmental scanning electron microscope and shear bond strength study

    OpenAIRE

    Chacko, Prince K; Kodoth, Jithesh; John, Jacob; Kumar, Kishore

    2013-01-01

    Aim: To determine the efficiency of erbium: Yttrium aluminum garnet (Er:YAG) laser with Environmental Scanning Electron Microscope (ESEM) and shear bond strength analysis as a method of recycling stainless steel orthodontic brackets and compare with other methods of recycling. Materials and Methods: Eighty samples of extracted premolar teeth bonded to SS brackets were tested for rebonded shear bond strength after recycling by four methods and compared with a control group of 20 samples. These...

  11. Multilayered polycrystalline iron garnet structure of Bi{sub 3}Fe{sub 5}O{sub 12} and Y{sub 3}Fe{sub 5}O{sub 12} grown on SiO{sub 2} substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, Timo; Heinrich, Andreas; Leitenmeier, Stephan; Herbort, Michael; Stritzker, Bernd [Universitaet Augsburg, EPIV, 86135 Augsburg (Germany); Simon, Juergen; Mader, Werner [Universitaet Bonn, Institut fuer Anorganische Chemie, Bonn (Germany)

    2007-07-01

    Iron Garnet single crystals like Y{sub 3}Fe{sub 5}O{sub 12} (YIG) are important ceramic systems with extensive applications in structural ceramics and optoelectronics. Currently, it is desirable to integrate such macroscopic components on a single chip (e.g. Si, SiO{sub 2},..) as in the case of microelectronics (integrated optics). High quality magnetooptical (MO) active garnet films with high Faraday rotation are also needed for MO imaging and microscopy. In our work we studied the influence of parameters during the deposition of YIG films and developed a new way to grow polycrystalline Bi{sub 3}Fe{sub 5}O{sub 12} (BIG) thin films on different SiO{sub 2} substrates using the pulsed laser deposition (PLD) method. Therefore we deposited a YIG buffer which was annealed above 1000 C in order to form a polycrystalline phase. On top of this buffer layer we deposited a thermodynamical unstable BIG layer. We measured the Faraday rotation of the films and studied them with x-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Environmental Scanning Electron Microscopy (ESEM) and high-resolution transmission electron spectroscopy (HRTEM). Their Faraday rotation can be compared with epitaxial BIG films grown on garnet substrates.

  12. Pulse-burst laser systems for fast Thomson scattering (invited)

    International Nuclear Information System (INIS)

    Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to ''pulse-burst'' capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned.

  13. Pulse-burst laser systems for fast Thomson scattering (invited).

    Science.gov (United States)

    Den Hartog, D J; Ambuel, J R; Borchardt, M T; Falkowski, A F; Harris, W S; Holly, D J; Parke, E; Reusch, J A; Robl, P E; Stephens, H D; Yang, Y M

    2010-10-01

    Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to "pulse-burst" capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned. PMID:21033868

  14. A picosecond thin-rod Yb:YAG regenerative laser amplifier with the high average power of 20 W

    International Nuclear Information System (INIS)

    A high-average-power, laser-diode-pumped, picosecond-pulse regenerative amplifier was developed using the thin-rod Yb:YAG (yttrium aluminum garnet) laser architecture. This architecture has a complete set of favorable properties for the cost-effective, high-average-power, and high-peak-power lasers. These include low amplified spontaneous emission with high gain and high repetition rate. For the amplifier system, an average output power of 20 W was achieved at a pulse repetition rate of 100 kHz, which corresponds to an output pulse energy of 200 μJ with an output pulse width of 2 ps. (letter)

  15. A picosecond thin-rod Yb:YAG regenerative laser amplifier with the high average power of 20 W

    Science.gov (United States)

    Matsubara, S.; Tanaka, M.; Takama, M.; Hitotsuya, H.; Kobayashi, T.; Kawato, S.

    2013-05-01

    A high-average-power, laser-diode-pumped, picosecond-pulse regenerative amplifier was developed using the thin-rod Yb:YAG (yttrium aluminum garnet) laser architecture. This architecture has a complete set of favorable properties for the cost-effective, high-average-power, and high-peak-power lasers. These include low amplified spontaneous emission with high gain and high repetition rate. For the amplifier system, an average output power of 20 W was achieved at a pulse repetition rate of 100 kHz, which corresponds to an output pulse energy of 200 μJ with an output pulse width of 2 ps.

  16. Wavelength-dependent magnetic transitions of self-organized iron–aluminum stripes induced by pulsed laser irradiation

    International Nuclear Information System (INIS)

    We investigate the laser wavelength dependence of structural and magnetic transitions on the surface of an iron–aluminum (FeAl) alloy induced by nanosecond pulsed laser irradiation. The formation of self-organized FeAl stripes with a wavelength-dependent period is observed in a local area on the (111)-oriented plane. Focused magneto-optical Kerr effect measurements reveal that the coercivity reaches up to 1.2 kOe with increasing the magnetic field rotation angle, which is estimated from the stripe direction, in FeAl stripes irradiated at 355 nm, and its magnetization reversal can be explained by the domain-wall motion model. On the other hand, the magnetization reversal agrees with the Stoner–Wohlfarth model in FeAl stripes irradiated at 1064 nm. This magnetic transition originates from the B2-to-A2 phase transition in stripe structures and bulk regions. These results indicate that the magnetic transition from the incoherent to coherent mode as well as the structural transformation of stripe patterns can be controlled by the incident laser wavelength

  17. Polymer optical waveguide composed of europium-aluminum-acrylate composite core for compact optical amplifier and laser

    Science.gov (United States)

    Mitani, Marina; Yamashita, Kenichi; Fukui, Toshimi; Ishigure, Takaaki

    2015-02-01

    We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

  18. Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Tatsuya [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: kiku@eng.hokudai.ac.jp; Sakairi, Masatoshi [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, Hideaki [Asahikawa National College of Technology, Syunkohdai, 2-2, 1-6, Asahikawa 071-8142 (Japan)

    2009-11-30

    Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-{mu}m wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing.

  19. Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

    International Nuclear Information System (INIS)

    Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-μm wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing.

  20. Effect of variation of magnetic field on laser ablation depth of copper and aluminum targets in air atmosphere

    Science.gov (United States)

    Singh, Khwairakpam Shantakumar; Sharma, Ashwini Kumar

    2016-05-01

    We report on the effect of transverse magnetic field on laser ablation of copper and aluminum targets both experimentally and numerically. The ablation depth is found to increase with magnetic field from 0 to 0.3 T and decreases at a higher magnetic field (0.5 T). It is demonstrated that the nanosecond laser ablation is mainly due to melt ejection and it solely depends on the thermo-physical parameters of the material. The increase in ablation depth with magnetic field is attributed to the increase in heat transfer from the plasma to the target, vapor pressure, and shock pressure. The ablation due to melt ejection is also calculated using vapor pressure through simulation and compared with the experimentally measured depth. In the presence of magnetic field, we introduce the magnetic pressure in Clausius-Clapeyron vapor pressure equation to account for the combined effect of magnetic field and atmospheric pressure on the vapor pressure of plasma. The ratio of calculated ablation depth at 0.3 T with respect to the absence of magnetic field is close to the corresponding experimental depth ratios indicating that the laser ablation modeling in the present work is validated. As the magnetic field increases, we observed the scattered mass at the center and around the crater. The size of deposited mass at the center is found to decrease at higher magnetic field which is attributed to breaking of large droplets into smaller ones due to increase in instability at higher magnetic field.

  1. Investigation of the crater-like microdefects induced by laser shock processing with aluminum foil as absorbent layer

    Science.gov (United States)

    Ye, Y. X.; Xuan, T.; Lian, Z. C.; Feng, Y. Y.; Hua, X. J.

    2015-06-01

    This paper reports that 3D crater-like microdefects form on the metal surface when laser shock processing (LSP) is applied. LSP was conducted on pure copper block using the aluminum foil as the absorbent material and water as the confining layer. There existed the bonding material to attach the aluminum foil on the metal target closely. The surface morphologies and metallographs of copper surfaces were characterized with 3D profiler, the optical microscopy (OM) or the scanning electron microscopy (SEM). Temperature increases of metal surface due to LSP were evaluated theoretically. It was found that, when aluminum foil was used as the absorbent material, and if there existed air bubbles in the bonding material, the air temperatures within the bubbles rose rapidly because of the adiabatic compression. So at the locations of the air bubbles, the metal materials melted and micromelting pool formed. Then under the subsequent expanding of the air bubbles, a secondary shock wave was launched against the micromelting pool and produced the crater-like microdefects on the metal surface. The temperature increases due to shock heat and high-speed deformation were not enough to melt the metal target. The temperature increase induced by the adiabatic compression of the air bubbles may also cause the gasification of the metal target. This will also help form the crater-like microdefects. The results of this paper can help to improve the surface quality of a metal target during the application of LSP. In addition, the results provide another method to fabricate 3D crater-like dents on metal surface. This has a potential application in mechanical engineering.

  2. Influence of surrounding gas, composition and pressure on plasma plume dynamics of nanosecond pulsed laser-induced aluminum plasmas

    Science.gov (United States)

    Dawood, Mahmoud S.; Hamdan, Ahmad; Margot, Joëlle

    2015-10-01

    In this article, we present a comprehensive study of the plume dynamics of plasmas generated by laser ablation of an aluminum target. The effect of both ambient gas composition (helium, nitrogen or argon) and pressure (from ˜5 × 10-7 Torr up to atmosphere) is studied. The time- and space- resolved observation of the plasma plume are performed from spectrally integrated images using an intensified Charge Coupled Device (iCCD) camera. The iCCD images show that the ambient gas does not significantly influence the plume as long as the gas pressure is lower than 20 Torr and the time delay below 300 ns. However, for pressures higher than 20 Torr, the effect of the ambient gas becomes important, the shortest plasma plume length being observed when the gas mass species is highest. On the other hand, space- and time- resolved emission spectroscopy of aluminum ions at λ = 281.6 nm are used to determine the Time-Of-Flight (TOF) profiles. The effect of the ambient gas on the TOF profiles and therefore on the propagation velocity of Al ions is discussed. A correlation between the plasma plume expansion velocity deduced from the iCCD images and that estimated from the TOF profiles is presented. The observed differences are attributed mainly to the different physical mechanisms governing the two diagnostic techniques.

  3. Numerical Analysis of Welding Residual Stress and Distortion in Laser+GMAW Hybrid Welding of Aluminum Alloy T-Joint

    Institute of Scientific and Technical Information of China (English)

    Guoxiang XU; Chuansong WU; Xuezhou MA; Xuyou WANG

    2013-01-01

    A 3-D finite element model is developed to predict the temperature field and thermally induced residual stress and distortion in laser+GMAW hybrid welding of 6061-T6 aluminum alloy T-joint.And the characteristics of residual stress distribution and deformation are numerically investigated.In the simulation,the heat source model takes into account the effect of joint geometric shape and welding torch slant on the heat flux distribution and a sequentially coupled thermo-mechanical method is used.The calculated results show that higher residual stress is distributed in and surround the weld zone.Its peak value is very close to the yield strength of base metal.Besides,a large deformation appears in the middle and rear part of the weldment.

  4. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    Science.gov (United States)

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-01

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm-2.

  5. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    International Nuclear Information System (INIS)

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm−2

  6. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Bidin, Noriah; Al-Wafi, Yusef A. [Advanced Photonic Science Institute, Faculty of Science, Universiti Teknologi Malaysia, Skudai, 81310, Johor (Malaysia)

    2014-03-05

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm{sup −2}.

  7. Garnet-to-perovskite transition in Gd3Sc2Ga3O12 at high pressure and high temperature.

    Science.gov (United States)

    Lin, Chuanlong; Liu, Jing; Lin, Jung-Fu; Li, Xiaodong; Li, Yanchun; Zhang, Qingli; Xiong, Lun; Li, Rui

    2013-01-01

    The structural phase transition of gadolinium-scandium-gallium garnet (Gd(3)Sc(2)Ga(3)O(12), GSGG) has been studied at high pressure and high temperature using the synchrotron X-ray diffraction technique in a laser-heated diamond anvil cell. The GSGG garnet transformed to an orthorhombic perovskite structure at approximately 24 GPa after laser heating to 1500-2000 K. The garnet-to-perovskite phase transition is associated with an ∼8% volume reduction and an increase in the coordination number of the Ga(3+) or Sc(3+) ion. The orthorhombic perovskite GSGG has bulk modulus B(0) = 194(15) GPa with B(0)' = 5.3(8), exhibiting slightly less compression than the cubic garnet structure of GSGG with B(0) = 157(15) GPa and B(0)' = 6.5(10). Upon compression at room temperature, the cubic GSGG garnet became amorphous at ∼65 GPa. Coupled with the amorphous-to-perovskite phase transition in Y(3)Fe(5)O(12) and Gd(3)Ga(5)O(12) at high-pressure-temperature conditions, we conclude that amorphization should represent a new thermodynamic state resulting from hindrance of the garnet-to-perovskite phase transition, whereas the garnet-to-amorphous transition in rare-earth garnets should be kinetically hindered at room temperature. PMID:23240758

  8. Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures

    International Nuclear Information System (INIS)

    Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1 atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1 atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures

  9. Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures

    Science.gov (United States)

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady; Hassanein, Ahmed

    2014-04-01

    Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1 atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1 atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

  10. Experimental determination of the temperature range of AlO molecular emission in laser-induced aluminum plasma in air

    International Nuclear Information System (INIS)

    Measurements with laser-induced breakdown spectroscopy (LIBS) usually take place in the atmospheric air. For quantitative analysis of metallic elements, oxidation may represent an important issue which can significantly modify the stoichiometry of the plasma. Molecule formation in plasma should be therefore studied and taken into account in the LIBS practice. In this work, we experimentally investigated the temporal evolution and transformation of the plasma induced on an aluminum target by a nanosecond infrared (1064 nm) laser in the atmospheric air, in terms of its temperatures over a large interval of time from hundreds of nanoseconds to tens of microseconds. Such evolution was then correlated to the temporal evolution of the emission intensity from AlO molecules in the ablation plume. In particular, for a given ablation laser pulse energy, the appearance of the molecular emission while the plume cools down allows determining a minimal delay, τmin, which corresponds to a maximal value of the temperature, Tmax, below which the molecular emission begins to be clearly observed and to grow as a function of the delay. Such delay or such temperature indicates the longest delay or the lowest temperature for laser-induced plasma to be suitable for a correct analysis of metallic elements without significant influence of the alternation of the stoichiometry by oxidation. In our experiment, the values of τmin and Tmax have been determined for a range of ablation laser pulse energies from 5 mJ to 50 mJ. These values lie respectively in the range of 3 to 15 μs for τmin, and 4500 K to 6600 K in terms of the molecule temperature for Tmax. Beyond the practical interest for LIBS, our results provide also insights to the kinetics of the AlO molecule formation in laser-induced plasma. - Highlights: • Determination of the temperatures in laser-induced plasma up to tens of microseconds • Determination of the molecule temperature by fitting the emission spectrum • The delay

  11. Laser removal of contaminants from aluminum surface using Q-switched Nd:YAG radiation at 1064, 532 and 355nm

    International Nuclear Information System (INIS)

    Radioactive contaminants on material surface must be decontaminated to reduce the radiation exposure of workers before the refurbishment of the old nuclear facilities. Laser ablation is a relatively new surface decontamination method and the method meets the following requirements: safety, high decontamination factor, cost-effectiveness, waste minimization and feasibility of industrialization. The objective of the work is to study the effect of wavelength on the removal of Cs+ and Co2+ ions on aluminum surfaces by laser. Laser beam from Q-switched Nd:YAG operating at the fundamental (1064nm), second harmonic (532nm) and third harmonic (355nm) wavelengths was irradiated on the surfaces of contaminated specimen

  12. Investigation of the crater-like microdefects induced by laser shock processing with aluminum foil as absorbent layer

    International Nuclear Information System (INIS)

    Highlights: • Crater-like microdefects formed on metal surface during laser shock process. • The air bubbles in the bonding material are responsible for forming microdefects. • Adiabatic compression of the air bubbles increases the temperature effectively. • Secondary shock wave induced by air bubbles is responsible for forming the defects. • Temperature increases due to shock heat and plastic deformation are limited. - Abstract: This paper reports that 3D crater-like microdefects form on the metal surface when laser shock processing (LSP) is applied. LSP was conducted on pure copper block using the aluminum foil as the absorbent material and water as the confining layer. There existed the bonding material to attach the aluminum foil on the metal target closely. The surface morphologies and metallographs of copper surfaces were characterized with 3D profiler, the optical microscopy (OM) or the scanning electron microscopy (SEM). Temperature increases of metal surface due to LSP were evaluated theoretically. It was found that, when aluminum foil was used as the absorbent material, and if there existed air bubbles in the bonding material, the air temperatures within the bubbles rose rapidly because of the adiabatic compression. So at the locations of the air bubbles, the metal materials melted and micromelting pool formed. Then under the subsequent expanding of the air bubbles, a secondary shock wave was launched against the micromelting pool and produced the crater-like microdefects on the metal surface. The temperature increases due to shock heat and high-speed deformation were not enough to melt the metal target. The temperature increase induced by the adiabatic compression of the air bubbles may also cause the gasification of the metal target. This will also help form the crater-like microdefects. The results of this paper can help to improve the surface quality of a metal target during the application of LSP. In addition, the results provide another

  13. Investigation of the crater-like microdefects induced by laser shock processing with aluminum foil as absorbent layer

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Y.X., E-mail: yeyunxia@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Xuan, T.; Lian, Z.C.; Feng, Y.Y.; Hua, X.J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China)

    2015-06-01

    Highlights: • Crater-like microdefects formed on metal surface during laser shock process. • The air bubbles in the bonding material are responsible for forming microdefects. • Adiabatic compression of the air bubbles increases the temperature effectively. • Secondary shock wave induced by air bubbles is responsible for forming the defects. • Temperature increases due to shock heat and plastic deformation are limited. - Abstract: This paper reports that 3D crater-like microdefects form on the metal surface when laser shock processing (LSP) is applied. LSP was conducted on pure copper block using the aluminum foil as the absorbent material and water as the confining layer. There existed the bonding material to attach the aluminum foil on the metal target closely. The surface morphologies and metallographs of copper surfaces were characterized with 3D profiler, the optical microscopy (OM) or the scanning electron microscopy (SEM). Temperature increases of metal surface due to LSP were evaluated theoretically. It was found that, when aluminum foil was used as the absorbent material, and if there existed air bubbles in the bonding material, the air temperatures within the bubbles rose rapidly because of the adiabatic compression. So at the locations of the air bubbles, the metal materials melted and micromelting pool formed. Then under the subsequent expanding of the air bubbles, a secondary shock wave was launched against the micromelting pool and produced the crater-like microdefects on the metal surface. The temperature increases due to shock heat and high-speed deformation were not enough to melt the metal target. The temperature increase induced by the adiabatic compression of the air bubbles may also cause the gasification of the metal target. This will also help form the crater-like microdefects. The results of this paper can help to improve the surface quality of a metal target during the application of LSP. In addition, the results provide another

  14. Emission Spectra Analysis of Aluminum Plasma Induced by Laser%激光诱导Al等离子体发射光谱分析

    Institute of Scientific and Technical Information of China (English)

    韩真真; 郝晓剑

    2014-01-01

    Laser-induced plasma technology is an important topic of the research on interaction between laser and material for a long time. The experiment system of laser induced plasma is researched and designed. Nd:YAG laser is used to induce Aluminum sample to produce plasma. And the Aluminum plasma emission spectra under dif⁃ferent energies are obtained. The element types contained in Aluminum sample and the changing relationship be⁃tween spectral line intensity and laser energy are analyzed. Experimental results show that the Aluminum sample contains Fe and Mg elements and with the increase of laser energy, spectra intensity increases obviously.%激光诱导等离子体技术长期以来都是研究激光与物质相互作用的重要课题。研究并设计了激光诱导等离子体实验系统,应用Nd:YAG激光器诱导Al样品产生等离子体,获得了不同能量下的Al等离子体发射光谱,分析了Al样品中所含元素种类以及谱线强度与激光能量之间的变化关系。实验结果表明,Al样品中含有Fe、Mg元素,随着激光能量的增大,谱线强度明显增大。

  15. Fusion cutting of aluminum, magnesium, and titanium alloys using high-power fiber laser

    Science.gov (United States)

    Scintilla, Leonardo Daniele; Tricarico, Luigi

    2013-07-01

    The effects of cutting speed and assist gas pressure on laser cutting of 1-mm thick Al 1050, AZ31, and Ti6Al4V lightweight alloys are experimentally investigated. Fiber laser cutting of these materials is not broadly investigated and the acquisition of a new level of knowledge is of fundamental importance for applications like sheet metal trimming in automotive industry. The main process outputs are in depth compared with results reported in literature and obtained by cutting with CO2 and Nd∶YAG lasers. The good cut quality, the high productivity, and the easy delivery of the beam obtained at the same time, corroborate the advantage of using fiber lasers for thin sheets lightweight alloys cutting.

  16. Improving interfacial reaction nonhomogeneity during laser welding-brazing aluminum to titanium

    International Nuclear Information System (INIS)

    Highlights: → Interfacial reaction nonhomogeneity of laser welding-brazing was improved. → The process window was extended by rectangular spot combined with V-shaped groove. → Mechanical property and its stability of Ti/Al dissimilar joint were enhanced. -- Abstract: Heterogeneous interfacial reactions were easily found along the Ti/Al interface due to high temperature gradient during laser welding-brazing of Ti/Al dissimilar alloys. To improve the nonhomogeneity, relative uniform energy distribution of laser beam and appropriate groove were attempted. The effects of these attempts on the nonhomogeneity of interfacial reactions were investigated by finite element method (FEM) numerical simulation and experimental validation. The results indicate that the V-shaped groove can make the interface roughly parallel to the isotherm of the temperature field. Moreover, the rectangular spot laser can further improve homogenization of the interfacial reaction along the interface in comparison with circular spot laser. Tensile test results show that the combination of rectangular spot laser welding-brazing and V-shaped groove can effectively control the fracture of Ti/Al joints in the seam in a wide processing parameters window, and the average tensile strength reaches 278 MPa.

  17. The effects of electron thermal radiation on laser ablative shock waves from aluminum plasma into ambient air

    Science.gov (United States)

    Sai Shiva, S.; Leela, Ch.; Prem Kiran, P.; Sijoy, C. D.; Chaturvedi, S.

    2016-05-01

    The effect of electron thermal radiation on 7 ns laser ablative shock waves from aluminum (Al) plasma into an ambient atmospheric air has been numerically investigated using a one-dimensional, three-temperature (electron, ion, and radiation) radiation hydrodynamic code MULTI. The governing equations in Lagrangian form are solved using an implicit scheme for planar, cylindrical, and spherical geometries. The shockwave velocities (Vsw) obtained numerically are compared with our experimental values obtained over the intensity range of 2.0 × 1010 to 1.4 × 1011 W/cm2. It is observed that the numerically obtained Vsw is significantly influenced by the thermal radiation effects which are found to be dominant in the initial stage up to 2 μs depending on the input laser energy. Also, the results are found to be sensitive to the co-ordinate geometry used in the simulation (planar, cylindrical, and spherical). Moreover, it is revealed that shock wave undergoes geometrical transitions from planar to cylindrical nature and from cylindrical to spherical nature with time during its propagation into an ambient atmospheric air. It is also observed that the spatio-temporal evolution of plasma electron and ion parameters such as temperature, specific energy, pressure, electron number density, and mass density were found to be modified significantly due to the effects of electron thermal radiation.

  18. Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

    International Nuclear Information System (INIS)

    Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system

  19. Bonding of adhesives to Er:YAG laser-treated dentin

    OpenAIRE

    Koliniotou-Koumpia, Eugenia; Kouros, Pantelis; Zafiriadis, Lazaros; Koumpia, Effimia; Dionysopoulos, Pavlos; Karagiannis, Vassilis

    2012-01-01

    Objective: The shear bond strength of adhesives applied to dentin was investigated after irradiation with an erbium-doped yttrium aluminum garnet (Er:YAG) laser. Methods: Superficial and deep dentin specimens from human molars were treated either with carbide bur or an Er:YAG laser. Two etch and rinse adhesives (Single Bond and XP Bond) and two self-etch adhesives (Prompt L-Pop and Xeno III) were employed to bond the composite. Shear bond strength (SBS) was determined after storage in water f...

  20. Spectral characteristics of arc plasma during laser-arc double-sided welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Kezhao Zhang; Zhenglong Lei; Xianglong Wang; Yanbin Chen; Yaobang Zhao

    2015-01-01

    In laser-arc double-sided welding,the spectral characteristics of the arc plasma are calculated and analyzed by spectroscopic diagnosis.The results show that,compared with conventional tungsten inert gas (TIG) welding,the introduction of a laser changes the physical characteristics of the arc plasma regardless of whether laser plasma penetration takes place,and that the influence of the laser mainly affects the near-anode region of the arc.When the laser power is relatively low,the arc column tends to compress,and the arc spectral characteristics show no significant difference.When the arc root constricts,compared with pure TIG arc,the electron density increases by ~2.7 times and the electron temperature decreases by ~3000 K.When the arc column expands,the intensities of spectral lines of both the metal and Ar atoms are the strongest.But it is also observed that the electron density reduces,whereas there is no obvious decrease of electron temperature.

  1. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

    OpenAIRE

    Sabina Luisa Campanelli; Giuseppe Casalino; Caterina Casavola; Vincenzo Moramarco

    2013-01-01

    Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the we...

  2. Laser-produced aluminum plasma expansion inside a plastic plasma envelope

    Czech Academy of Sciences Publication Activity Database

    Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Parys, P.; Renner, Oldřich; Gus´kov, S.Y.; Demchenko, N. N.; Ullschmied, Jiří; Krouský, Eduard; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří

    2012-01-01

    Roč. 19, č. 9 (2012), s. 1-8. ISSN 1070-664X R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA ČR GAP205/10/0814 Grant ostatní: 7FP LASER LAB-EUROPE(XE) 228334 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser -mater interaction * plasma jets production * x-ray spectroscopy * particle plasma diagnosis * ion charge density * plasma temperature Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.376, year: 2012

  3. Transmyocardial Laser Revascularization.

    Science.gov (United States)

    Horvath, Keith A.

    2004-02-01

    Transmyocardial laser revascularization (TMR) has been performed on over 12,000 patients worldwide. Since 1990, the treatment has provided significant angina relief for symptomatic end-stage coronary disease that is refractory to medical therapy. Seventy-five percent of patients treated with TMR have demonstrated a decrease of two or more angina classes postoperatively. As a result, TMR has provided a significant improvement in quality of life for patients, resulting in fewer hospital admissions and decreased dependency on medications. Two different wavelengths of light, carbon dioxide (CO(2)) and holmium yttrium-aluminum-garnet (Ho:YAG), have been employed. Results obtained using these lasers differ. The CO(2) laser has demonstrated a perfusion benefit as well as long-term improvement in quality of life and angina relief. The Ho:YAG laser has not demonstrated these results. These differences may, in part, explain the failure of percutaneous myocardial laser revascularization. This catheter-based approach was not as successful as TMR due to its partial thickness treatment of the myocardium as well as its use of the Ho:YAG laser. In addition to the patients with end-stage coronary disease who undergo TMR as sole therapy, there are an increasing number of patients who have been treated with a combination of coronary artery bypass grafting and TMR. This provides a more complete revascularization than leaving territories ungrafted. Further enhancement of the angiogenic response seen after TMR may be seen by the addition of gene therapy to TMR treatment. PMID:15023284

  4. Local deposition of polypyrrole on aluminum by anodizing, laser irradiation, and electrolytic polymerization and its application to the fabrication of micro-actuators

    International Nuclear Information System (INIS)

    Polypyrrole was deposited at selected areas on aluminum by anodizing, laser irradiation, and electrolytic polymerization, and the application of the technique for fabricating micro-actuators was attempted. Aluminum specimens covered with porous type anodic oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally, and then thin Ni layers were deposited at areas where film had been removed. Polypyrrole could be successfully deposited only on the Ni layer by anodic polarization of the specimens in pyrrole monomer solution, and a polypyrrole/Ni bilayer structure could be obtained by dissolution of the aluminum substrate and anodic oxide film in NaOH solutions. The bilayer structure was found to be inactive to doping and dedoping of ions during anodic and cathodic polarization. A three-layer structure, nitrocellulose/Ni/polypyrrole, fabricated by electrolytic polymerization after nitrocellulose coating on a Ni layer detached from the aluminum substrate, showed ion-doping and -dedoping activity, suggesting the possibility of fabricating micro-actuators in this manner

  5. Radiation hardness of Nd:YAG and Nd:Cr:GSGG laser rods

    International Nuclear Information System (INIS)

    Gadolinium scandium gallium garnett (GSGG) co-doped with neodymium (Nd) and chromium (Cr), shows higher efficiency and optical damage threshold than commonly used neodymium doped yttrium aluminum garnet (Nd:YAG) laser rod. Nd:YAG and Nd:Cr:GSGG laser rods were irradiated with gamma radiation from Cobalt-60 source. Passive electronic and vibrational spectra of the laser materials were obtained before and after radiation. The near ultraviolet (NUV), visible (VIS) and near infrared (NIR) spectra were obtained using a spectrophotometer. The data collected indicates that the Nd:YAG laser rod had transient radiation effects while the Nd:Cr:GSGG laser rod appeared to be resistant to the effects of the radiation dose in terms of the laser's output energy

  6. Experimental study of solar pumped laser for magnesium-hydrogen energy cycle

    International Nuclear Information System (INIS)

    24.4 W of laser output has been obtained by sun-pumped, Cr-codoped Nd:yttrium aluminum garnet ceramic. The water-cooled laser rod was pumped with a Fresnel lens focusing the natural sunlight. By using the advantages of the Fresnel lenses, the maximum output for unit area of sunlight was 18.7 W/m2. Direct concentrated solar illumination was used to pump a 9mm-diameter, 100mm length rod of Cr:Nd:YAG, which was obtained 9%-14% slope efficiency for the laser output. We have analyzed the Cr:YAG laser medium and found it to be an excellent high-power laser candidate for direct solar-pumping schemes which enhances the laser output about 1.8 times more than Nd:YAG

  7. The effects of lasers and electrosurgical devices on human meniscal tissue.

    Science.gov (United States)

    Sherk, H H; Black, J D; Prodoehl, J A; Diven, J

    1995-01-01

    The purpose of this study was to evaluate the effects of various laser wavelengths on human meniscal tissue in vitro and to compare them with the effects of electrosurgical devices. The carbon dioxide (CO2) laser produced the best cutting and ablating effects among the infrared lasers, although the contact neodymium:yttrium-aluminum-garnet (Nd:YAG) and holmium:YAG (Ho:YAG)lasers were nearly as satisfactory, offering the additional advantage of fiberoptic capability and the ability to be used in saline. The free-beam Nd:YAG laser and coagulation mode electrosurgical device produced unacceptably severe thermal changes. The excimer laser at 308 nm produced the best tissue effect and caused no detectable adjacent thermal change in the tissue. PMID:7641430

  8. Investigation of the technology of laser welding of aluminum alloy 1424

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Antipov, V. V.; Ioda, E. N.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-12-01

    In this study, certain technological variants of the laser welding of alloy 1424 of the Al-Mg-Li-Zr system are considered with the purpose of obtaining the durability level of the welded joint, which is close to that of the basic metal. It is shown that, in the case of using various types of plastic deformation of the welded joint, its durability can be increased considerably to 0.85-0.95 from that of the basic metal.

  9. Studies of the mechanisms involved in the laser surface hardening process of aluminum base alloys

    International Nuclear Information System (INIS)

    The Al-Si alloys are widely used in industry to replace the steel and gray cast iron in high-tech sectors. The commercial importance of these alloys is mainly due to its low weight, excellent wear (abrasion) and corrosion resistance, high resistance at elevated temperatures, low coefficient of thermal expansion and lesser fuel consumption that provide considerable reduction of emission of pollutants. In this work, Al-Si alloy used in the automotive industry to manufacture pistons of internal combustion engines, was undergone to surface treatments using LASER remelting (Nd:YAG, λ = 1.06 μm, pulsed mode). The LASER enables various energy concentrations with accurate transfer to the material without physical contact. The intense energy transfer causes the occurrence of structural changes in the superficial layer of the material. Experiments with single pulses and trails were conducted under various conditions of LASER processing in order to analyze microstructural changes resulting from treatments and their effects on the hardness. For the characterization of hardened layer was utilized the following techniques: optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray mapping, Vickers microhardness and maximum roughness tests. The high cooling rate caused a change in the alloy structure due to the refinement of the primary eutectic silicon particles, resulting in increase of the mechanical properties (hardness) of the Al-Si alloy. (author)

  10. Pr.sup.3+./sup.-doped aluminium garnet crystals and layers

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Beitlerová, Alena; Nikl, Martin; Nitsch, Karel; Kučera, M.; Hanuš, M.

    Bratislava: Slovak Expert Group of Solid State Chemistry and Physics , 2011 - (Koman, M.; Jorík, V.), 42-43 ISBN 978-80-8134-002-4. [Joint Seminar – Development of materials science in research and education (DMRSE)/21.th./. Kežmarské Žlaby (SK), 29.08.2011-02.09.2011] Institutional research plan: CEZ:AV0Z10100521 Keywords : Pr 3+ -doped * aluminum garnet crystals * layers * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism

  11. Crystal growth of large size Dy3Al5O12 garnet single crystals

    Science.gov (United States)

    Kimura, Hideo; Sakamoto, Masaru; Numazawa, Takenori; Sato, Mitsunori; Maeda, Hiroshi

    1990-01-01

    Crystal growth conditions using the Czochralski technique were examined in order to be able to grow large-size disprosium-aluminum-garnet single crystals; these are useful as a working material in a practical magnetic refrigeration system. Using the best conditions, large-size bubble-free Dy3Al5O12 single crystals 50 mm in diameter were grown from a stoichiometric melt composition using a seed of Y3Al5O12 single crystal.

  12. K-edge shift and XANES investigation of laser driven reshock-compressed Aluminum

    Science.gov (United States)

    Benuzzi-Mounaix, Alessandra; Ravasio, Alessandra; Koenig, Michel; Festa, Floriane; Amadou, Nourou; Levy, Anna; Brambrink, Erik; Dorchies, Fabien; Peyrusse, Olivier; Mazevet, Stéphane; Recoules, Vanina; Hall, Tom

    2010-11-01

    The physical properties of warm dense matter, specially their structural properties, are still poorly known. In this work, K-edge shift and X-ray Absorption Near Edge Spectroscopy (XANES) of reshocked Aluminum have been investigated with the aim of bringing information on the evolution of its electronic structure. The experiment was performed at LULI where we used one long pulse (500 ps, IL 8 10^13 W/cm^2) to create the shock and a second picosecond beam (IL 10^17 W/cm^2) to generate an ultra-short broadband X-ray source near the Al K-edge. The spectra were registered by using two conical KAP Bragg crystals. By changing the delay between the two beams, we have been able to observe the modification of absorption spectra for different and extreme Al conditions, up to now unexplored (ρ <= 3 ρ0 and T <= 8 eV). The hydrodynamical Al conditions were measured by using VISARs interferometers and self-emission diagnostic. Experimental data are compared to various calculations.

  13. Stoichiometry and characterization of aluminum oxynitride thin films grown by ion-beam-assisted pulsed laser deposition

    International Nuclear Information System (INIS)

    Oxides are inherently stable in air at elevated temperatures and may serve as wear resistant matrices for solid lubricants. Aluminum oxide is a particularly good candidate for a matrix because it has good diffusion barrier properties and modest hardness. Most thin film deposition techniques that are used to grow alumina require high temperatures to impart crystallinity. Crystalline films are about twice as hard as amorphous ones. Unfortunately, the mechanical properties of most engineering steels are degraded at temperatures above 250-350 deg. C. This work is focused on using energetic reactive ion bombardment during simultaneous pulsed laser deposition to enhance film crystallization at low temperatures. Alumina films were grown at several background gas pressures and temperatures, with and without Ar ion bombardment. The films were nearly stoichiometric except for depositions in vacuum. Using nitrogen ion bombardment, nitrogen was incorporated into the films and formed the Al-O-N matrix. Nitrogen concentration could be controlled through selection of gas pressure and ion energy. Crystalline Al-O-N films were grown at 330 deg. C with a negative bias voltage to the substrate, and showed improved hardness in comparison to amorphous films

  14. Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

    Science.gov (United States)

    Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

    2015-09-01

    We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed. PMID:26271017

  15. Investigation on effect of laser shock processing on fatigue crack initiation and its growth in aluminum alloy plate

    International Nuclear Information System (INIS)

    Highlights: • LSP can greatly delay crack formation. • The micro-crack growing processes and its fracture are showed clearly. • Surface topographies and crack initiation locations are displayed. - Abstract: A series of contrasting experiments were carried out to examine the effects of laser shock processing (LSP) on fatigue properties of slot in 7075-T6 aluminum alloy plate. Both side surfaces of slot were subjected to LSP. The surface topographies were observed and the residual stresses were tested. The treated and the un-treated specimens were pulled by the fatigue cyclic loading respectively. The fatigue crack propagating processes were recorded, and the fatigue fracture microscopic morphologies were analyzed by scanning electron microscope (SEM). Experimental results and analyses show that LSP induces micro-dent on surface and squeezes the compressive residual stresses into surface layer of specimen. It can remarkably delay the micro-crack formation, and transfer the location of fatigue crack initiation from top surface to sub-surface. The spacing of fatigue striations on the treated specimen fatigue fracture obviously decreases. Therefore, the fatigue life of specimen after LSP treatment significantly increases

  16. Scintillation properties of Yb-doped yttrium-aluminum garnets

    International Nuclear Information System (INIS)

    Relative light yield (LY) dependence on temperature for Yb:YAG crystals containing 10% to 100% of Yb dopant is studied for γ and α excitation. The maximum LY is achieved at 120 K3 Ph/MeV at T=140 K for (Yb 25%) YAG. Linearity of the light output is checked. α/γ ratio is found to be 0.42±0.02. Pulse shapes induced by γ and α particles and cosmic rays are investigated by analysing a set of single events recorded. γ events are fast (τ<4 ns), while other kinds of radiation give rise to more complicated and longer profiles, allowing particle discrimination. Dependence of scintillation properties on concentration of Yb and purity is discussed

  17. High excitation of the species in nitrogen–aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

    International Nuclear Information System (INIS)

    A reactive nitrogen–aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen–aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis. - Highlights: • ECR discharge and pulsed laser ablation generate highly excited ECR–PLA plasma. • The expansion of PLA plasma results in excitation enhancement of ECR plasma species. • The ECR plasma leads to excitation prolongation of PLA plasma species. • The ECR–PLA plasma emits strong emissions from a variety of excited species. • The ECR–PLA plasma maintains high vibrational–rotational temperatures for a long time

  18. Pulsed-CO2-laser interaction with aluminum in air: Thermal response and plasma characteristics

    International Nuclear Information System (INIS)

    Simultaneous target heating, plasma spectral emission, and time-resolved plasma interferometry data were taken for the interaction of CO2 (lambda2, the pulse duration was 1.8 μs, and the maximum peak flux on target was 8 x 107 W/cm2. The target thermal response is analyzed to provide both the total energy deposited on target and the spatial distribution of the energy. The total energy deposited increases in direct proportion to the laser-pulse energy, with a coupling coefficient of 18% above the plasma ignition threshold

  19. Characterizing laser fusion welded aluminum using synchrotron x-ray microtomography

    International Nuclear Information System (INIS)

    Preliminary research into the application of high power Nd-YAG lasers for welding indicate a dependency of the occurrence of weld discontinuities on processing parameters such as pulse duty cycle, travel speed, etc. The size and distribution of weld features have been characterized using synchrotron microtomography, using facilities at the National Synchrotron Light Source. The ability of this technique to image defects such as gross and minor porosity, and centerline cracking, enables a metrology of interior surfaces which cannot be provided by metallurgical sectioning techniques alone

  20. In vitro analysis of laser meniscectomy.

    Science.gov (United States)

    Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

    1995-01-01

    Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air. PMID:7641441

  1. Multiwavelength green-yellow laser based on a Nd:YAG laser with nonlinear frequency conversion in a LBO crystal.

    Science.gov (United States)

    Wang, Zhichao; Yang, Feng; Xie, Shiyong; Xu, Yiting; Xu, Jialin; Bo, Yong; Peng, Qinjun; Zhang, Jingyuan; Cui, Dafu; Xu, Zuyan

    2012-06-20

    We demonstrate a multiwavelength laser in the green-yellow region by means of a diode-pumped neodymium-doped yttrium aluminum garnet laser. This laser system combines a homemade 1074 nm and 1112 nm dual-wavelength laser with extracavity second harmonic generation (SHG) or sum-frequency generation in a lithium triborate crystal to generate visible output at any one of three wavelengths, 537 nm, 546 nm, and 556 nm, by simple temperature tuning, which has an important application in detecting carbon monoxide. The maximum average output power at the three wavelengths (537 nm, 546 nm, and 556 nm) was obtained to be 10.5 W, 0.5 W, and 8.5 W, respectively. The maximum SHG conversion efficiency from the infrared to the visible spectral region was about 51%. PMID:22722297

  2. A graphene-based passively Q-switched Ho:YAG laser in-band pumped by a diode-pumped Tm:YLF solid-state laser

    International Nuclear Information System (INIS)

    We report the first demonstration of a Ho:YAG (yttrium aluminum garnet) solid-state laser passively Q-switched via a graphene saturable absorber. The Ho:YAG laser was in-band pumped by a continuous wave diode-pumped Tm:YLF (yttrium lithium fluoride) laser. Double-layer graphene grown by chemical vapor deposition and transferred onto a thin quartz plate was fabricated as the saturable absorber. We observed basically stable Q-switched laser pulses at the center wavelength of 2096.5 nm with the shortest pulse width of 632 ns, a repetition rate of 43 kHz, and the single-pulse energy of 13.3 μJ. Our results illustrate that graphene can be used well as a saturable absorber in a Ho-doped solid-state laser at 2 μm wavelength. (paper)

  3. Research in gadolinium scandium gallium garnet (GSGG) crystal development. Final report, 1 May-31 December 1984

    International Nuclear Information System (INIS)

    The Czochralski growth technique was utilized for the development of a large diameter, laser quality gadolinium, scandium gallium garnet co-doped with neodymium and chromium (Nd:Cr:GSGG). Vary aspects of the development were determinations of raw material purity, foule growth runs, boule composition and lattice parameters, and losses. 8 refs., 13 figs., 10 tabs

  4. Numerical Investigation of Keyhole Shape during CO2 Laser Welding of 5456 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available This paper takes a close look at the keyhole shape forming process as well as the effect thermal heat flow has on weld penetration depth. Laser heat input is one of the main determinants of keyhole formation, weld penetration, and fusion morphology. In this study, it was found that the dominant solute transport in the weldpool is driven by convection with a maximum velocity of 1.57 m/s, above the value of 1.0m/s reported by other investigators. This further confirms the turbulent nature of the flow in the weldpool. The droplet shape in the keyhole was found to be conical. The fusion depth and width were calculated to be 1.04mm and 4.26mm respectively. These values were compared with reported values of other investigators and the results were within acceptable ranges.

  5. Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

    Science.gov (United States)

    Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

    2016-04-01

    Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

  6. Dry metal forming of high alloy steel using laser generated aluminum bronze tools

    Directory of Open Access Journals (Sweden)

    Freiße Hannes

    2015-01-01

    Full Text Available Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the tool and sheet material. The potential to generate tailored tribological systems for dry metal forming could be shown within the investigations by using different material combinations and by applying different laser cladding process parameters. Furthermore, the feasibility of additive manufacturing of a deep drawing tool was demonstrated. The tool was successfully applied to form circular cups in a dry metal forming process.

  7. Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

    Science.gov (United States)

    Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

    2016-08-01

    Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

  8. Microstructure and Strength of Laser Welds of Sub-micron Particulate-reinforced Aluminum Martix Composite Al2O3p/6061Al

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al2O3p/6061Al and the weldability of the material were studied.Experimental results indicated that because of the huge specific surface area of the reinforcement,the interfacial reaction between the matrix and the reinforcement was restrained intensively at elevated temperature and pulsed laser beam.The main factor affecting the weldability of the composite was the reinforcement segregation in the weld resulting from the push of the liquid/solid interface during the solidification of the molten pool.The laser pulse frequency directly affected the reinforcement segregation and the reinforcement distribution in the weld,so that the weldability of the composite could be improved by increasing the laser pulse frequency.On the bases of this,a satisfactory welded joint of sub-micron particulate-reinforced aluminum matrix composite Al2Op/6061Al was obtained by using appropriate welding parameters.

  9. Sealing ability of mineral trioxide aggregate, calcium phosphate and polymethylmethacrylate bone cements on root ends prepared using an Erbium: Yttriumaluminium garnet laser and ultrasonics evaluated by confocal laser scanning microscopy

    Directory of Open Access Journals (Sweden)

    C Sabari Girish

    2013-01-01

    Full Text Available Background: Surgical endodontic therapy comprises of exposure of the involved root apex, resection of the apical end of the root, preparation of a class I cavity, and insertion of a root end filling material. Mineral trioxide aggregate (MTA is now the gold standard among all root end filling materials. MTA is however difficult to handle, expensive and has a very slow setting reaction. Aim: (1 To compare the sealing ability of MTA, polymethylmethacrylate (PMMA bone cement and CHITRA Calcium phosphate cement (CPC when used as root end filling material using Rhodamine B dye evaluated under a confocal laser scanning microscope. (2 To compare the seal of root ends prepared using an ultrasonic retroprep tip and an Er: YAG laser using three different root end filling materials. Statistical Analysis: Statistical analysis was performed using a one-way ANOVA and a two-way ANOVA, independent samples t-test and Scheffe′s post hoc test using SPSS Version 16 for Windows. Results: All the three materials, namely MTA, PMMA BONE CEMENT and CHITRA CPC, showed microleakage. Comparison of microleakage showed maximum peak value of 0.86 mm for MTA, 0.24 mm for PMMA bone cement and 1.37 mm for CHITRA CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er: YAG laser when compared with ultrasonics, but the difference was found to be not statistically significant. Conclusion: PMMA bone cement is a better material as root end filling material to prevent apical microleakage. MTA still continues to be a gold standard root end filling material showing minimum microleakage. Er: YAG laser is a better alternative to ultrasonics for root end preparations.

  10. Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

    International Nuclear Information System (INIS)

    We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5 nm at variable laser pulse widths between 200 ps and 25 ns. The plasma target was a 30 μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5 nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25 ns at an intensity of 5x1010 W/cm2

  11. Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

    Science.gov (United States)

    Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

    2007-05-01

    We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5nm at variable laser pulse widths between 200ps and 25ns. The plasma target was a 30μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25ns at an intensity of 5×1010W/cm2.

  12. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the H{sub α} line profiles and Thomson scattering spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cvejić, M., E-mail: marko.cvejic@ipb.ac.rs, E-mail: krzysztof.dzierzega@uj.edu.pl [Institute of Physics, University of Belgrade, P.O. Box 68, 11080 Belgrade (Serbia); Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Dzierżęga, K., E-mail: marko.cvejic@ipb.ac.rs, E-mail: krzysztof.dzierzega@uj.edu.pl; Pięta, T. [M. Smoluchowski Institute of Physics, Jagellonian University, ul. Łojasiewicza 11, 30-348 Kraków (Poland)

    2015-07-13

    We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the H{sub α}, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the H{sub α} full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

  13. Laser removal of contaminants from aluminum surface using Q-switched Nd:YAG radiation at 1064, 532 and 355nm

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sun Hee; Won, Hui Jun; Choi, Byung Seon; Moon, Jei Kwon; Jung, Chong Hun; Lee, Kune Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-05-15

    Radioactive contaminants on material surface must be decontaminated to reduce the radiation exposure of workers before the refurbishment of the old nuclear facilities. Laser ablation is a relatively new surface decontamination method and the method meets the following requirements: safety, high decontamination factor, cost-effectiveness, waste minimization and feasibility of industrialization. The objective of the work is to study the effect of wavelength on the removal of Cs{sup +} and Co{sup 2+} ions on aluminum surfaces by laser. Laser beam from Q-switched Nd:YAG operating at the fundamental (1064nm), second harmonic (532nm) and third harmonic (355nm) wavelengths was irradiated on the surfaces of contaminated specimen

  14. Probe for portable laser induced breakdown spectroscopy of molten aluminum and cryolite

    OpenAIRE

    Úlfar Karl Arnórsson 1988

    2014-01-01

    Við álframleiðslu þarf að fylgjast stöðugt með hreinleika álsins ásamt efnafræðilegri byggingu raflausnarinnar sem notuð er til að rafgreina áloxíð í hreint ál. Í dag er sýni tekið af raflausninni og álbráðinni, sýnin eru steypt og meðhöndluð áður en það fer í greiningu á rannsóknarstofu. Ferlið er langt og stýringar keranna vinna stöðugt eftir gömlum upplýsingum. Í þessu verkefni eru vandamálin við að beita ,,laser induced breakdown spectroscopy“ eða LIBS tækni til frumefnagreiningar á...

  15. Interference effects and Stark broadening in XUV intrashell transitions in aluminum under conditions of intense XUV free-electron-laser irradiation

    Science.gov (United States)

    Galtier, E.; Rosmej, F. B.; Calisti, A.; Talin, B.; Mossé, C.; Ferri, S.; Lisitsa, V. S.

    2013-03-01

    Quantum mechanical interference effects in the line broadening of intrashell transitions are investigated for dense plasma conditions. Simulations that involved LSJ-split level structure and intermediate coupling discovered unexpected strong line narrowing for intrashell transitions L-L while M-L transitions remained practically unaffected by interference effects. This behavior allows a robust study of line narrowing in dense plasmas. Simulations are carried out for XUV transitions of aluminum that have recently been observed in experiments with the FLASH free-electron laser in Hamburg irradiating solid aluminum samples with intensities greater than 1016 W/cm2. We explore the advantageous case of Al that allows, first, simultaneous observation of M-L transitions and L-L intrashell transitions with high-resolution grating spectrometers and, second, has a convenient threshold to study interference effects at densities much below solid. Finally, we present simulations at near solid density where the line emission transforms into a quasicontinuum.

  16. Flaw Inspection of Aluminum Pipes by Non-Contact Visualization of Circumferential Guided Waves using Laser Ultrasound Generation and an Air-Coupled Sensor

    International Nuclear Information System (INIS)

    Our group had previously proposed a generation laser scanning system for visualizing ultrasound propagation on an object as an animate image, which provided visible and quick flaw inspection. Recently, we improved this system to make it completely non-contact by employing an air-coupled ultrasound transducer as a receiver instead of a contact transducer, and demonstrated the successful visualization of Lamb waves propagating on aluminum and carbon fiber reinforced plastic plates, as well as the detection of flaws. In this research, we applied this system to the non-contact visualization of circumferential guided waves on aluminum pipes. It was shown that circumferential guided waves propagating in opposite directions could be visualized separately, and that a flaw such as a slit or thinning on the inside surface of the pipe could be successfully detected even when it existed outside the scanning area

  17. Dislocation polymorphism transformation of 6061-T651 aluminum alloy processed by laser shock processing: Effect of tempering at the elevated temperatures

    International Nuclear Information System (INIS)

    The effects of tempering on surface topography and dislocation configuration of 6061-T651 aluminum alloy by laser shock processing (LSP) were investigated at the elevated temperatures. Surface topography and surface roughness were tested by a Surfcom 130A-Monochrome surface rough-meter. Morphologies of precipitated phases were monitored by scanning electron microscopy (SEM), and the dislocation configurations of samples after LSP were characterized by transmission electron microscope (TEM). The results showed that LSP had a beneficial effect on micro-hardness at elevated temperature. There was a little change of the surface roughness as subjected to LSP. The main strengthening mechanism of micro-hardness was dislocation strengthening and fine grain strengthening, and precipitated phase strengthening was the main strengthening mechanism at elevated temperature. “Dislocation polymorphism transformation” (DPT) effect was affirmed at elevated temperature, and the elevated temperature was principal element for inducing the DPT effect of 6061-T651 aluminum alloy by LSP

  18. Characterization of an Aluminum Alloy Hemispherical Shell Fabricated via Direct Metal Laser Melting

    Science.gov (United States)

    Holesinger, T. G.; Carpenter, J. S.; Lienert, T. J.; Patterson, B. M.; Papin, P. A.; Swenson, H.; Cordes, N. L.

    2016-03-01

    The ability of additive manufacturing to directly fabricate complex shapes provides characterization challenges for part qualification. The orientation of the microstructures produced by these processes will change relative to the surface normal of a complex part. In this work, the microscopy and x-ray tomography of an AlSi10Mg alloy hemispherical shell fabricated using powder bed metal additive manufacturing are used to illustrate some of these challenges. The shell was manufactured using an EOS M280 system in combination with EOS-specified powder and process parameters. The layer-by-layer process of building the shell with the powder bed additive manufacturing approach results in a position-dependent microstructure that continuously changes its orientation relative to the shell surface normal. X-ray tomography was utilized to examine the position-dependent size and distribution of porosity and surface roughness in the 98.6% dense part. Optical and electron microscopy were used to identify global and local position-dependent structures, grain morphologies, chemistry, and precipitate sizes and distributions. The rapid solidification processes within the fusion zone (FZ) after the laser transit results in a small dendrite size. Cell spacings taken from the structure in the middle of the FZ were used with published relationships to estimate a cooling rate of ~9 × 105 K/s. Uniformly-distributed, nanoscale Si precipitates were found within the primary α-Al grains. A thin, distinct boundary layer containing larger α-Al grains and extended regions of the nanocrystalline divorced eutectic material surrounds the FZ. Subtle differences in the composition between the latter layer and the interior of the FZ were noted with scanning transmission electron microscopy (STEM) spectral imaging.

  19. Pressure Induced Amorphization in Garnets investigated by X-ray Diffraction and Spectroscopic techniques

    Science.gov (United States)

    Hua, Hong; Vohra, Yogesh K.

    1996-03-01

    We report the first direct observation of pressure induced amorphization in garnets GGG and GSGG at ambient temperature(both are Cr^3+, Nd^3+ doped). Laser spectroscopic studies show abrupt disappearance of fluorescent emission peaks at high pressure due to loss of the long range order. The amorphization was confirmed by the synchrotron x-ray diffraction studies at X-17C, NSLS. The amorphization pressure for GSGG is 58±3GPa and for GGG is 90±5GPa. The transformation pressures for the garnets are correlated to the strength of the crystal field. The amorphous phase can be quenched at ambient conditions. The amorphization phenomenon in garnets is explained on the basis of a three-level thermodynamic model. (Supported by NSF Grant No. DMR-9403832)

  20. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  1. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    International Nuclear Information System (INIS)

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθ stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 μm line width were obtained successfully

  2. Experimental demonstration of a dual-frequency laser free from anti-phase noise

    OpenAIRE

    El Amili, Abdelkrim; Loas, Goulc'Hen; De, Syamsundar; Schwartz, Sylvain; Feugnet, Gilles; Pocholle, Jean-Paul; Bretenaker, Fabien; Alouini, Mehdi

    2012-01-01

    A reduction of more than 20 dB of the intensity noise at the anti-phase relaxation oscillation frequency is experimentally demonstrated in a two-polarization dual-frequency solid-state laser without any optical or electronic feedback loop. Such a behavior is inherently obtained by aligning the two orthogonally polarized oscillating modes with the crystallographic axes of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The anti-phase noise level is shown to increase as soon ...

  3. Diode-pumped multilayer Yb:YAG composite ceramic laser

    International Nuclear Information System (INIS)

    All-ceramic multilayer composite ytterbium doped yttrium aluminum garnet (Yb:YAG) laser gain medium with doping concentration distribution of 0-5-10-15-20-15-10-5-0 at.% Yb ions was successfully fabrication by the technique of tape casting and simple vacuum sintering process. Full dense microstructure is achieved, and excellent optical properties are gained. The obtained result shows that the optical transmittance of >80% is reached when the wavelength is larger than 500 nm. The emission cross section is 4.03×10-20 cm2 at the wavelength of 1030 nm. Continuous wave (CW) laser performance is further demonstrated when the sample is pumped by 940 nm fiber-coupler diode laser. The threshold absorbed pump power is 5.9 W, and the slope efficiency attains to 27% with transmission of output coupler of 6%

  4. Garnet ships in a quartzite sea

    Science.gov (United States)

    Rogowitz, Anna; Rice, A. Hugh N.; Grasemann, Bernhard; Huet, Benjamin

    2016-04-01

    During progressive deformation, a strong inclusion in a weaker matrix causes a stress concentration that may result in strain localization, seen in a matrix grain-size reduction. A superb example of this phenomena, but rather more complex, has been observed in north Norwegian Caledonides. A probably subvertical metadolerite dyke has been rotated to lie parallel to the penetrative regional low-angled foliation during the emplacement of the overlying nappe. The metadolerite, now only ~1.4 cm thick and lying between two quartzite layers has been retrogressed to a biotite schist with an assemblage of biotite, titanite, epidote group, garnet and quartz. Garnets are from 0.2 mm to 4 cm in size, subhedral and have two growth zones, with inclusions of predominantly titanite and rare amphibole. The country-rock metasedimentary schists contain staurolite, indicating mid-amphibolite-facies conditions (~550 °C and 6 kbar). During late deformation, some garnets were forced into the quartzite, resulting in the development of pronounced gouges (tectoglyphs), up to 70 mm long, 14 mm wide and 14 mm deep, deepening in the direction of movement. Quartz was pushed up at the sides of the gouges and forms a pronounced bow-wave at the front of the garnets. Where garnets are gouged into the quartzite, intense strain localization occurs. Both in front of and under the garnet, a up to 18 mm wide zone of quartz mylonite developed. The mylonitic foliation curves around the garnet, with a relatively sharp boundary to the adjacent quartzite that preserves an older random fabric. Deformation in the mylonite, which shows a strong crystallographic preferred orientation, seems to have occurred by (1) intense dislocation glide followed by (2) subgrain rotation resulting in an almost foam-like fabric. The grain size of the mylonite (at the quartzite-biotite schist interface) increases with increasing distance behind the present position of the garnets. This observation is consistent with an expected

  5. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    International Nuclear Information System (INIS)

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  6. Spatially-Resolved Crystallization of Amorphous Silicon Films on the Glass Substrate by Multi-beam Laser Interference

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Laser interference induced crystallization of amorphous silicon (a-Si) on the glass substrate was performed using a Q-switched Nd:YAG (yttrium aluminum garnet) laser. White light interferometer (WLI) and atomic force microscope (AFM) were used to characterize the morphology of the structured films, while X-ray diffraction (XRD), combined with the AFM, was used to analyse the crystalline structure of the film. The experimental results show that the laser energy density above a certain threshold, in the range of 400-500 mJ/cm2,triggers the patterned crystallizations which take the form similar to the laser intensity distribution. For the patterned crystallization under multipulse exposure, a definite polycrystalline structure with individual phases was observed by XRD. The difference in feature form, e.g., deepened craters or heightened lines, is related to the laser energy density relative to the threshold of evaporation of the material.

  7. Bouveret's syndrome complicated by distal gallstone ileus after laser lithotropsy using Holmium: YAG laser

    Directory of Open Access Journals (Sweden)

    Rodgers John B

    2002-06-01

    Full Text Available Abstract Background Bouveret's syndrome is an unusual presentation of duodenal obstruction caused by the passage of a large gallstone through a cholecystoduodenal fistula. Endoscopic therapy has been used as first-line treatment, especially in patients with high surgical risk. Case presentation We report a 67-year-old woman who underwent an endoscopic attempt to fragment and retrieve a duodenal stone using a Holmium: Yttrium-Aluminum-Garnet Laser (Ho:YAG which resulted in small bowel obstruction. The patient successfully underwent enterolithotomy without cholecystectomy or closure of the fistula. Conclusion We conclude that, distal gallstone obstruction, due to migration of partially fragmented stones, can occur as a possible complication of laser lithotripsy treatment of Bouveret's syndrome and might require urgent enterolithotomy.

  8. Effects of laser irradiation on aluminum alloy tank containing water%1053nm脉冲激光对铝合金/水结构辐照效应

    Institute of Scientific and Technical Information of China (English)

    焦路光; 赵国民; 袁立国

    2011-01-01

    Experimental measurement and numerical simulation are employed to study the effects of laser irradiation on aluminum alloy tank containing water. Firstly, by analyzing the surface pictures and measuring the temperature histories, the effects of water on the ablation of aluminum alloy plate irradiated by I 053 nm pulsed laser are investigated. The results show that heat conduction and convection play a very important role in the ablation of the aluminum alloy plate. When the tank is empty, the aluminum alloy plate is melt through after eight laser pulses irradiation. And when the tank is filled with water, the aluminum alloy plate has not been melt through after ten laser pulses irradiation. Then, a numerical model is presented to calculate the temperature distribution of the aluminum alloy tank, and the dimension of the region that has melted is obtained. The difference between the numerical result and the experimental result is not apparent when the tank is empty, but when the tank is filled with water the difference is a little large. The reason is that the natural convection and boiling of water are not considered in the numerical model.%使用1053 nm脉冲激光分别辐照铝合金单板和铝合金/水结构,通过表面形貌观察、温度场分析、熔穿时间测量等手段,分析了水的存在对铝合金壳体烧蚀的影响.运用有限元软件ANSYS,建立了脉冲激光辐照下单板及结构温度变化的数值模型,计算了铝合金表面熔凝区域的尺寸,并与实验结果进行了对比.结果表明:在相同的实验条件下,辐照8个激光脉冲时,铝合金单板即被熔穿,而辐照10个脉冲后铝合金/水结构仍未发生熔穿,且结构中铝合金表面的熔凝区域要小于单板情形中的熔凝区域,这表明水的存在对延缓铝合金板的烧蚀有较大的作用.对于单板情形,计算结果与实验结果符合较好,而对于铝合金/水结构情形,数值模拟放大了铝合金壳体的温升,这主

  9. Diode pumped highly efficient Yb:Lu3Al5O12 ceramic laser

    International Nuclear Information System (INIS)

    A diode pumped ytterbium-doped lutetium aluminum garnet (Yb:LuAG) ceramic laser is reported for the first time to our knowledge. Using the solid state reactive vacuum sintering technique we have successfully fabricated high optical quality Yb:LuAG ceramics. We show that even with an uncoated Yb:LuAG ceramic sample a maximum output power of 7 W could be achieved under 13 W absorbed pump power, and the laser has a slope efficiency as high as 63%. Considering that Yb:LuAG has higher thermal conductivity than Yb:YAG under heavy doping situation, Yb:LuAG ceramic could be an attractive laser gain medium for the high power solid state lasers applications

  10. Preliminary report: comparison of 980-nm, 808-nm diode laser enhanced with indocyanine green to the Nd:YAG laser applied to equine respiratory tissue

    Science.gov (United States)

    Tate, Lloyd P.; Blikslager, Anthony T.; Campbell, Nigel B.

    2001-05-01

    The Neodynium: Yttrium Aluminum Garnet (Nd:YAG) laser has been the mainstay of performing upper respiratory laser surgery in the equine since 1984. The 808-nm diode laser has also been applied transendoscopically as well as the 980-nm diode laser over recent years. It has been shown that Indocyanine Green (ICG) enhances the performance of the 808- nm laser because it is absorbed at 810 nm of light. The 808- nm laser's tissue interaction combined with ICG is equivalent to or greater than the Nd:YAG laser's cutting ability. The 980-nm diode laser performance was similar to that of the Nd:YAG as determined by the parameters of this study. This study compared the depths and widths of penetration achieved with the 808-nm diode laser after intravenous injection of ICG on equine respiratory tissue. It also compared depths and widths of penetration achieved by the non-contact application of the 980-nm diode laser delivering the same energy of 200 joules. The depths and widths of penetration of both diode lasers were compared to themselves and to the Nd:YAG laser with all factors remaining constant.

  11. Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source

    International Nuclear Information System (INIS)

    A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 μm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2x1011 W/cm2 with a spot diameter of 175 μm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal

  12. Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source

    Science.gov (United States)

    Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

    2007-03-01

    A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 μm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2×1011 W/cm2 with a spot diameter of 175 μm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal.

  13. Laser-induced photodynamic therapy with aluminum phthalocyanine tetrasulfonate as the photosensitizer: Differential phototoxicity in normal and malignant human cells in vitro

    International Nuclear Information System (INIS)

    Photodynamic therapy (PDT) involves the use of laser or noncoherent light energy with photosensitizing dyes to induce a cytotoxic reaction in the target cells, resulting in cell injury and/or death. In this study, we have examined laser-induced phototoxicity in normal human skin fibroblasts and HT-1080 fibrosarcoma cells incubated with aluminum phthalocyanine tetrasulfonate (AlPcS) in vitro. The culture, laser, and photosensitizer parameters were varied in attempts to establish the conditions for differential cytotoxicity between normal and malignant human fibroblasts. Biochemical assays, as a measure of cytotoxicity, included [3H]thymidine incorporation (an index of DNA replication), [35S]methionine incorporation (a measure of protein synthetic activity), and the MTT assay (an indirect index of mitochondrial activity). In the absence of laser irradiation, AlPcS was non-toxic to both cell lines in concentrations up to 25 micrograms/ml. Laser light alone at 675 nm (the absorption maximum of AlPcS) had no effect on the cells at energy densities up to 16 J/cm2. In the presence of 3 or 10 micrograms/ml of AlPcS, both cell lines demonstrated marked energy-dependent toxicity. If an 8-h or a 24-h efflux period in AlPcS-free medium was allowed to take place prior to laser irradiation, normal fibroblasts were much less sensitive to PDT, whereas fibrosarcoma cells still exhibited a marked degree of toxicity. The results indicate that, under appropriate treatment conditions, AlPcS is capable of preferentially sensitizing a malignant mesenchymal cell line, while sparing its non-malignant normal cell counterpart

  14. Systematic hardness measurements on some rare earth garnet crystals

    Indian Academy of Sciences (India)

    D B Sirdeshmukh; L Sirdeshmukh; K G Subhadra; K Kishan Rao; S Bal Laxman

    2001-10-01

    Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium gallium garnet, there was no measurable difference in the hardness values of pure and nominally Nd-doped crystals. The hardness values were correlated with the lattice and elastic constants. An analysis of hardness data in terms of the interatomic binding indicated a high degree of covalency.

  15. Enhancement of the electron electric dipole moment in gadolinium garnets

    OpenAIRE

    Mukhamedjanov, T. N.; Dzuba, V. A.; Sushkov, O. P.

    2003-01-01

    Effects caused by the electron electric dipole moment (EDM) in gadolinium garnets are considered. Experimental studies of these effects could improve current upper limit on the electron EDM by several orders of magnitude. We suggest a consistent theoretical model and perform calculations of observable effects in gadolinium gallium garnet and gadolinium iron garnet. Our calculation accounts for both direct and exchange diagrams.

  16. Aluminum Hydroxide

    Science.gov (United States)

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  17. Focused ion beam and electron microscopy characterization of nanosharp tips and microbumps on silicon and metal thin films formed via localized single-pulse laser irradiation

    International Nuclear Information System (INIS)

    Cross-sections of laser fabricated nanosharp tips and microbumps on silicon and metal thin films are produced and examined in this work. These structures are formed with a Q-switched neodymium doped yttrium aluminum garnet nanosecond-pulse laser, emitting at its fourth harmonic of 266 nm, using a mask projection technique to generate circular laser spots, several microns in diameter. Cross-section of selected structures were produced using a focused ion beam and were characterized via electron microscopy. The diffraction patterns of the silicon samples indicate that the laser formed tip maintains the same single crystal structure as the original silicon film. Examinations of the laser formed structures in metal films confirm that the microbumps are hollow, while revealing that the vertical protrusions are solid.

  18. Aluminum microstructures on anodic alumina for aluminum wiring boards.

    Science.gov (United States)

    Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki

    2010-03-01

    The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide film of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices. PMID:20356280

  19. Random Laser Action in Nd:YAG Crystal Powder

    Directory of Open Access Journals (Sweden)

    Jon Azkargorta

    2016-05-01

    Full Text Available This work explores the room temperature random stimulated emission at 1.064 μm of a Nd:YAG crystal powder (Neodymium-doped yttrium aluminum garnet in a very simple pump configuration with no assistance from an internal mirror. The laser threshold energy as a function of pump beam area and pump wavelength has been measured, as well as the temporal dynamics of emission pulses. The absolute energy of stimulated emission and the absolute laser slope efficiency have been measured by using a method proposed by the authors. The results show a surprising high efficiency that takes the low Nd3+ ion concentration of the crystal powder into account.

  20. Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

    Science.gov (United States)

    Lorusso, Massimo; Aversa, Alberta; Manfredi, Diego; Calignano, Flaviana; Ambrosio, Elisa Paola; Ugues, Daniele; Pavese, Matteo

    2016-06-01

    Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

  1. Effect of welding wires on microstructure and mechanical properties of 2A12 aluminum alloy in CO2 laser-MIG hybrid welding

    International Nuclear Information System (INIS)

    This paper represented the effect of welding wires on microstructure and mechanical properties of 2A12 aluminum alloy in CO2 laser-metal inter gas (MIG) hybrid welding. Plates of 2A12 aluminum alloy were welded by ER4043 and ER2319 welding wires, respectively. Full penetration joints without any defects were produced. The X-ray diffraction was used to analyze the phase composition, while the scanning electron microscopy (SEM) was conducted to study the microstructure, segregation behaviors of major alloying elements and the eutectics formed at dendrite boundaries in the joints. The results showed that silicon and copper were concentrated at the dendrite boundaries and α-Al + Si + Al2Cu + Mg2Si eutectic was formed if the ER4043 welding wire was used. However, only copper was concentrated at the dendrite boundaries and α-Al + θ eutectic was formed by ER2319 welding wire. Finally, the tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint efficiency by ER2319 and ER4043 welding wires reached up to 78% and 69%, respectively. Coarse dimples and voids had been observed in the fractographs. The joints showed a transgranular type failure.

  2. Dynamics expansion of laser produced plasma with different materials in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rabia Qindeel; Noriah Bte Bidin; Yaacob Mat daud [Laser Technology Laboratory, Physics Department, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)], E-mail: plasmaqindeel@yahoo.com

    2008-12-01

    The dynamics expansion of the plasma generated by laser ablation of different materials has been investigated. The dynamics and confinement of laser generated plasma plumes are expanding across variable magnetic fields. A Q-switched neodymium-doped yttrium aluminum garnet laser with 1064 nm, 8 ns pulse width and 0.125 J laser energy was used to generate plasma that was allowed to expand across variable magnetic within 0.1 - 0.8 T. The expansions of laser-produced plasma of different materials are characterized by using constant laser power. CCD video camera was used to visualize and record the activities in the focal region. The plasma plume length, width and area were measured by using Matrox Inpector 2.1 and video Test 0.5 software. Spectrums of plasma beam from different materials are studied via spectrometer. The results show that the plasma generated by aluminum target is the largest than Brass and copper. The optical radiation from laser generated plasma beam spectrums are obtained in the range of UV to visible light.

  3. In situ measurement of the particle size distribution of the fragmentation product of laser-shock-melted aluminum using in-line picosecond holography

    Directory of Open Access Journals (Sweden)

    Ying-Hua Li

    2016-02-01

    Full Text Available The dynamic fragmentation of shock-melted metal is a topic of increasing interest in shock physics. However, high-quality experimental studies of the phenomenon are limited, and data that are essential for developing predictive models of the phenomenon, such as the mass and particle sizes distributions, are quite sparse. In-line holography is an effective non-contact technique for measuring particle size distribution, but critical technical requirements, in particular, particle density limits, complicate its application to the subject phenomenon. These challenges have been reasonably overcome in the present study, allowing for successful in situ measurements of the size distribution of the fragmentation product from laser-shock-melted aluminum. In this letter, we report on our experiments and present the measured data.

  4. Effects of different shocked paths on fatigue property of 7050-T7451 aluminum alloy during two-sided laser shock processing

    International Nuclear Information System (INIS)

    The tensile samples manufactured by 7050 aluminum (Al) alloy were treated by different shocked paths during two-sided laser shock processing (LSP), and the samples were divided into two groups according to these different paths. The first group was treated by two paths, while the second group was treated by four paths. The fatigue tests were performed on a servo-hydraulic material testing machine system by using the stepped loading method named Locati. The fracture morphology was observed by scanning electron microscopy (SEM). Experimental results showed that the fatigue lives of the second group increased compared to those of the first group. The effects of different shocked paths on fracture morphology during two-sided LSP were discussed. Furthermore, the enhancement mechanism of different shocked paths on fatigue crack initiation and growth two-sided LSP was also addressed during.

  5. Microtensile bond strength of different adhesive systems in dentin irradiated with Er:YAG laser

    International Nuclear Information System (INIS)

    The objective this study was to evaluate in vitro the bond strength of two etch-and-rise and one self-etching adhesive system after dentin irradiation with Er:YAG (erbium: yttrium aluminum garnet) laser using microtensile test. The results revealed that the groups treated with laser Er:YAG presented less tensile bond strength, independently to the adhesive system used. The prompt L-pop adhesive presented less microtensile bond strength compared to the other adhesives evaluated. There was no difference between single bond and excite groups. The adhesive failures were predominant in all the experimental groups. The Er:YAG laser influenced negatively bond strength values of adhesive systems tested in dental substrate

  6. Recent developments in polycrystalline oxide fiber laser materials: production of Yb-doped polycrystalline YAG fiber

    Science.gov (United States)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian; Parthasarathy, Triplicane; Cheng, Michael; Hopkins, Frank K.

    2011-09-01

    Laser quality, polycrystalline oxide fibers offer significant advantages over state-of-the-art silica fiber for high energy lasers. Advanced ceramic processing technology, along with a novel powder production process, has potential to produce oxide fibers with an outstanding optical quality for use in the fiber laser applications. The production of contaminant-free green fibers with a high packing density, as well as uniform packing distribution, is a key factor in obtaining laserquality fibers. High quality green fibers are dependent on the powder quality combined with the appropriate slurry formulation. These two fundamental technologies were successfully developed at UES, and used to produce Yb-doped yttrium aluminum garnet (YAG) fibers with high optical quality, high chemical purity, and suitable core diameters down to 20-30 microns.

  7. Laser-induced plasma spectroscopy of hydrogen Balmer series in laboratory air.

    Science.gov (United States)

    Swafford, Lauren D; Parigger, Christian G

    2014-01-01

    Stark-broadened emission profiles for the hydrogen alpha and beta Balmer series lines in plasma are measured to characterize electron density and temperature. Plasma is generated using a typical laser-induced breakdown spectroscopy (LIBS) arrangement that employs a focused Q-switched neodymium-doped yttrium aluminum garnet (Nd : YAG) laser, operating at the fundamental wavelength of 1064 nm. The temporal evolution of the hydrogen Balmer series lines is explored using LIBS. Spectra from the plasma are measured following laser-induced optical breakdown in laboratory air. The electron density is primarily inferred from the Stark-broadened experimental data collected at various time delays. Due to the presence of nitrogen and oxygen in air, the hydrogen alpha and beta lines become clearly discernible from background radiation for time delays of 0.4 and 1.4 μs, respectively. PMID:25226255

  8. Characterization of laser beam interaction with carbon materials

    International Nuclear Information System (INIS)

    This paper presents simulation and experimental results for the exposure of some carbon-based materials to alexandrite and Nd3+:YAG (yttrium aluminum garnet) laser radiation. Simulation of the heating effects was carried out using the COMSOL Multiphysics 3.5 package for samples of carbon-based P7295-2 fiber irradiated using an alexandrite laser and carbon-based P4396-2 fiber irradiated using an Nd3+:YAG laser, as well as by applying finite element modeling for P7295-2 samples irradiated using an Nd3+:YAG laser. In the experimental part, P7295-2 samples were exposed to alexandrite laser radiation while samples of carbon-based composite 3D C/C were exposed to Nd3+:YAG laser radiation. Micrographs of the laser induced craters were obtained by light and scanning electron microscopy, and the images analyzed using the ImageJ software. The results obtained enable identification of the laser–material interaction spots, and characterization of the laser induced changes in the materials investigated. (paper)

  9. Fusion welding of Fe-added lap joints between AZ31B magnesium alloy and 6061 aluminum alloy by hybrid laser-tungsten inert gas welding technique

    International Nuclear Information System (INIS)

    Highlights: → Hybrid Laser-TIG fusion welding technique was used for joining Mg to Al alloys. → Laser defocusing amount determined penetration depth inside Al alloy of joints. → The addition of Fe interlayer suppressed Mg-Al intermetallics greatly in joints. → A maximum joint strength with optimum thickness of Fe interlayer was obtained. → Excessive addition of Fe interlayer was adverse for the strength improvement. -- Abstract: AZ31B magnesium alloy and 6061-T6 aluminum alloy were lap joined together with the addition of Fe interlayer by fusion welding of hybrid laser-tungsten inert gas (TIG) technique. The influence of location of laser focal spot (LFS) on joint penetration depth and that of the depth on joint strength were investigated. The results showed that when the LFS was just on the surface of Al plate, the deepest penetration could be obtained, which contributed to the improvement of shear strength of Fe-added joints, but not to the elevation of the strength of Mg/Al direct joints. The addition of Fe interlayer suppressed massive production of Mg-Al intermetallics but produced Fe-Al intermetallics in the fusion zone of the joints, whose micro-hardness was extremely high and was also adverse for the enhancement of joint shear strength. The effect of Fe-interlayer thickness on the joint shear strength was also examined, and the maximum shear strength of Fe-added joint could achieve 100 MPa with 0.13 mm thick Fe interlayer. The fracture modes of 0.07 and 0.13 mm Fe-interlayer-added joints were both quasi-cleavage, while those of direct and 0.22 mm interlayer-added joints were completely cleavage. The theoretical shear strength of the Fe-added joints was also discussed.

  10. Laser Peening and Shot Peening Effects on Fatigue Life and Surface Roughness of Friction Stir Welded 7075-T7351 Aluminum

    Science.gov (United States)

    Hatamleh, Omar; Lyons, Jed; Forman, Royce

    2006-01-01

    The effects of laser peening, shot peening, and a combination of both on the fatigue life of Friction Stir Welds (FSW) was investigated. The fatigue samples consisted of dog bone specimens and the loading was applied in a direction perpendicular to the weld direction. Several laser peening conditions with different intensities, durations, and peening order were tested to obtain the optimum peening parameters. The surface roughness resulting from various peening techniques was assessed and characterized. The results indicate a significant increase in fatigue life using laser peening compared to shot peened versus their native welded specimens.

  11. Metasomatic Control of Water in Garnet and Pyroxene from Kaapvaal Craton Mantle Xenoliths

    Science.gov (United States)

    Peslier, Anne H.; Woodland, Alan B.; Bell, David R.; Lazarov, Marina; Lapen, Thomas J.

    2012-01-01

    Fourier transform infrared spectrometry (FTIR) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used to determine water, rare earth (REE), lithophile (LILE), and high field strength (HFSE) element contents in garnet and pyroxene from mantle xenoliths, Kaapvaal craton, southern Africa. Water enters these nominally anhydrous minerals as protons bonded to structural oxygen in lattice defects. Pyroxene water contents (150-400 ppm in clinopyroxene; 40-250 ppm in orthopyroxene) correlate with their Al, Fe, Ca and Na and are homogeneous within a mineral grains and a xenolith. Garnets from Jagersfontein are chemically zoned for Cr, Ca, Ti and water contents. Garnets contain 0 to 20 ppm H2 Despite the fast diffusion rate of H in mantle m inerals, the observations above indicate that the water contents of mantle xenolith minerals were not disturbed during kimberlite entrainment and that the measured water data represent mantle values. Trace elements in all minerals show various degrees of light REE and LILE enrichments indicative of minimal to strong metasomatism. Water contents of peridotite minerals from the Kaapvaal lithosphere are not related to the degree of depletion of the peridotites. Instead, metasomatism exerts a clear control on the amount of water of mantle minerals. Xenoliths from each location record specific types of metasomatism with different outcomes for the water contents of mantle minerals. At pressures . 5.5 GPa, highly alkaline melts metasomatized Liqhobong and Kimberley peridotites, and increased the water contents of their olivine, pyroxenes and garnet. At higher pressures, the circulation of ultramafic melts reacting with peridotite resulted in co-variation of Ca, Ti and water at the edge of garnets at Jagersfontein, overall decreasing their water content, and lowered the water content of olivines at Finsch Mine. The calculated water content of these melts varies depending on whether the water content of the peridotite

  12. Amorphous Structures in Laser Cladding of ZL111 Aluminum Alloy:Semi-quantitative Study by Differential Thermal Analysis (DTA)

    Institute of Scientific and Technical Information of China (English)

    LI Xianqin; CHENG Zhaogu; XIA Jin'an; XU Guoliang; LIANG Gongying

    2000-01-01

    This paper deals with amorphous structures in the laser cladding. ZL111 alloy is the substrate and Ni-Cr-Al alloy is sprayed on the substrate as the coating material. The coating is clad by a 5 kW transverse flow CO2 laser. The observation of SEM and TEM reveal that in the laser cladding there are amorphous structures of two different morphologies: one is space curved flake-like, and exists in the white web-like structures; the other is fir leaf-like, and exists in the grain-like structures. Differential thermal analysis (DTA) is used to semi-quantitatively determine the content of the amorphous structures. A relation is obtained between the content of amorphous structures and the dimensionless laser cladding parameter C. We also show the changes of the amorphous structures after annealing.

  13. Measuring solid-state quantum yields: The conversion of a frequency-doubled Nd:YAG diode laser pointer module into a viable light source.

    Science.gov (United States)

    Daglen, Bevin C; Harris, John D; Dax, Clifford D; Tyler, David R

    2007-07-01

    This article outlines the difficulties associated with measuring quantum yields for solid-state samples using a high-pressure mercury arc lamp as the irradiation source. Details are given for the conversion of an inexpensive frequency-doubled neodymium-doped yttrium aluminum garnet (Nd:YAG) diode laser pointer module into a viable irradiation source. The modified Nd:YAG laser was incorporated into a computer-controlled system, which allowed for the simultaneous irradiation and spectroscopic monitoring of the sample. The data obtained with the Nd:YAG diode laser system show far less scatter than data obtained with a high-pressure Hg arc lamp, and consequently the degradation rates obtained with the laser system could be calculated with far greater accuracy. PMID:17672778

  14. Microstructure and Wear Behaviour of Laser-induced Thermite Reaction Al2O3 Ceramic Coating on AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    Kaijin HUANG; Xin LIN; Changsheng XIE; T.M. Yue

    2007-01-01

    The microstructure and wear behaviour of the thermite reaction coating produced by the hybrid laser claddingremelting on AA7075 aluminum alloy for the systems of Al-CuO-SiO2, Al-Cr2O3-SiO2, Al-Fe2O3-SiO2, and Al-TiO2-SiO2 were studied. The results of the X-ray diffraction (XRD) analysis show that in all the four reaction coatings, α-Al2O3 and γ-Al2O3 phases were present at the top surface, together with various intermetallic phases, the corresponding reduced metal and Al phase in the fusion zone. Under the dry sliding condition, the wear resistance, in terms of weight loss, of the laser-clad specimens was considerably higher than that of the untreated specimen. The predominant wear mechanism of the former specimens was abrasive wear, while for the latter, it was the adhesive wear that prevailed.

  15. Flashlamp pumped lasing performance of Cr/sup 3+/:GdScGa-Garnet

    International Nuclear Information System (INIS)

    Chromium doped GdScGa-Garnet (Cr:GSGG) exhibits broadband fluorescence in the 700-900 nm region. Growth of this material and lasing at 790 nm with laser pumping was previously reported. Another work subsequently reported flashlamp pumped lasing of a 3.9 mm by 40 m Cr:GSGG rod. In this paper, the authors report on lasing performance of a flashlamp pumped Cr:GSGG laser rod and its lasting threshold for different operating temperatures. Evidence is presented that points to excited state absorption as a limiting factor in this material's performance

  16. Laser application in tracheobronchial tumors

    Science.gov (United States)

    Rau, B. Krishna; Krishna, Sharon

    2004-09-01

    Ninety three patients with obstructing tracheobronchial tumors were treated with Neodymium: Yttrium - Aluminum - Garnet (Nd:YAG) laser photocoagulation over a period of six years. There were sixty seven Males and 26 Females with a mean age of 44.3 years (range 6- 79 years). 21 benign and 72 malignant lesions were treated with a total 212 sessions of laser photocoagulation (mean 2.4 sessions). The anatomical distribution of lesions were as follows; larynx 9 (three benign and 6 malignant) trachea 39 (27 benign and 12 malignant) left main bronchus 27 (14 malignant) right main bronchus 24 (14 malignant) and vocal cords - 9 (three malignant). There were 21 patients with squamous cell carcinoma, two adenocarcinomas, one adenoid cystic carcinoma, 7 cases of locally infiltrating tumors from thyroid and esophagus, 6 cases of carcinoid tumor and 16 benign lesions. Twenty one patients had a tracheostomy tube in place when treatment was started. Eighteen of the 21 patients with tracheostomy were weaned off the tube in a mean of 5.5 days from the start of treatment. Lumen was restored in 31 (79.4%) patients. In the other eight (20.6%), lumen was achieved, but not sustained. Complications included bleeding in three cases which were managed conservatively, two cases of pneumothorax, and four cases of bronchospasm. There were six deaths during the follow up but none attributable to the procedure. Laser photocoagulation offered effective treatment in the majority of patients with obstructing tracheobronchial tumors, with acceptable morbidity.

  17. Polycrystalline Garnet Porphyroblasts, an EBSD Study

    Science.gov (United States)

    Seaton, N. C.; Whitney, D. L.; Anderson, C.; Alpert, A.

    2008-12-01

    Polycrystalline garnet porphyroblasts (PGP's) are significant because their formation provides information about metamorphic crystalline mechanisms, in particular during early stages of crystal growth, which may differ from those governing later stages; and because their existence may affect the chemical and structural evolution of metamorphic rocks. For example, the extent of element exchange between the garnet interior and the matrix may be affected by the presence of grain boundaries within PGP's. There have been several previous studies of PGP's but important questions about them remain; e.g. whether early coalescence is a common method by which garnets crystallize, whether grains rotate during growth to attain an energetically favorable grain-grain contact, and whether deformation and/or precursor minerals or other chemical or mechanical heterogeneities influence the formation of PGP's. PGP's have been detected by us in several different localities including; micaschist from SE Vermont (USA), including locality S35j of Rosenfeld (1968); the Solitude Range (British Columbia, Canada); the Southern Menderes Massif (Turkey); and three zones (garnet, staurolite, kyanite) from the Dutchess County Barrovian sequence in NY (USA). We have identified two types of PGP: cryptic and morphologically distinct. Cryptic PGP have no obvious morphological expression of the high angle boundaries within them and appear to be a single crystal. Morphologically distinct PGP have an obvious depression in the outer grain boundary where it is intersected by the internal grain boundary. Most PGP's contain inclusion trails and the high angle grain boundaries crosscut the trend of these as well as the inclusions themselves. PGP also show major element growth zoning that is not influenced by the internal grain boundaries except in rare cases. PGP's comprise ~ 5-35% of the garnet populations analyzed. More than 95% of the PGP's we have analyzed are comprised of 2-3 domains; the rest contain

  18. Thickness- and temperature-dependent magnetodynamic properties of yttrium iron garnet thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haidar, M., E-mail: mohammad.haidar@Physics.gu.se; Ranjbar, M.; Balinsky, M.; Dumas, R. K. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Khartsev, S. [Department of Integrated Devices and Circuits, School of ICT, Royal Institute of Technology (KTH), 16440 Kista (Sweden); Åkerman, J. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Materials Physics, School of ICT, Royal Institute of Technology (KTH), 16440 Kista (Sweden)

    2015-05-07

    The magnetodynamical properties of nanometer-thick yttrium iron garnet films are studied using ferromagnetic resonance as a function of temperature. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition. First, we found that the damping coefficient increases as the temperature increases for different film thicknesses. Second, we found two different dependencies of the damping on film thickness: at room temperature, the damping coefficient increases as the film thickness decreases, while at T = 8 K, we find the damping to depend only weakly on the thickness. We attribute this behavior to an enhancement of the relaxation of the magnetization by impurities or defects at the surfaces.

  19. Phase field simulation of kinetic superheating and melting of aluminum nanolayer irradiated by pico- and femtosecond laser

    International Nuclear Information System (INIS)

    Two melting mechanisms are reproduced and quantified for superheating and melting of Al nanolayer irradiated by pico- and femtosecond laser using the advanced phase-field approach coupled with mechanics and a two-temperature model. At heating rates Q≤79.04 K/ps induced by picosecond laser, two-sided barrierless surface melting forms two solid-melt interfaces, which meet near the center of a sample. The temperature for surface melting is a linear function, and for complete melting it is a cubic function, of logQ. At Q≥300 K/ps induced by femtosecond laser, barrierless and homogeneous melting (without nucleation) at the sample center occurs faster than due to interface propagation. Good agreement with experimental melting time was achieved in a range of 0.95≤Q≤1290 K/ps without fitting of material parameters

  20. Phase field simulation of kinetic superheating and melting of aluminum nanolayer irradiated by pico- and femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Seok Hwang, Yong [Department of Aerospace Engineering, Iowa State University, Ames, Iowa 50011 (United States); Levitas, Valery I. [Departments of Aerospace Engineering, Mechanical Engineering, and Material Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2013-12-23

    Two melting mechanisms are reproduced and quantified for superheating and melting of Al nanolayer irradiated by pico- and femtosecond laser using the advanced phase-field approach coupled with mechanics and a two-temperature model. At heating rates Q≤79.04 K/ps induced by picosecond laser, two-sided barrierless surface melting forms two solid-melt interfaces, which meet near the center of a sample. The temperature for surface melting is a linear function, and for complete melting it is a cubic function, of logQ. At Q≥300 K/ps induced by femtosecond laser, barrierless and homogeneous melting (without nucleation) at the sample center occurs faster than due to interface propagation. Good agreement with experimental melting time was achieved in a range of 0.95≤Q≤1290 K/ps without fitting of material parameters.

  1. Composition of garnets in the fossil geothermal system of Hafnarfjall

    OpenAIRE

    Haraldur Sigurjónsson 1987

    2016-01-01

    Garnet is an important high temperature index mineral in geothermal systems. At Hafnarfjall samples were collected from the fossil geothermal system within the caldera that has been exposed by erosion, these samples were found to contain garnets. The geothermal system was caused by a gabbro intrusion that formed by multiple intrusions of dolerite, this overode the previous geothermal system along the caldera fault. This was also observed in the composition of garnets related to quartz veins. ...

  2. Recent results of the laser ion source facility at INFN-LNS and applications to nuclear and applied research

    International Nuclear Information System (INIS)

    A pulsed neodymium-doped yttrium aluminum garnet laser ion source has been used as proton beams generator. The laser wavelength is 1064 nm, the pulse duration is 9 ns and the intensity reaches 1010 W/cm2. Laser irradiates hydrogenated polymers targets located in a chamber at 10-7 mbar. The ions are post-accelerated in a suitable chamber by 30 kV of voltage between the target, positively biased, and the following ground electrode. The extracted beams is characterized through a time-of-flight technique. Possible applications to the field of nuclear physics, such as nuclear excitation and de-excitations, nuclear reactions and nuclear fusion, will be presented and discussed.

  3. Effects of striated laser tracks on thermal fatigue resistance of cast iron samples with biomimetic non-smooth surface

    International Nuclear Information System (INIS)

    In order to enhance the thermal fatigue resistance of cast iron materials, the samples with biomimetic non-smooth surface were processed by Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser. With self-controlled thermal fatigue test method, the thermal fatigue resistance of smooth and non-smooth samples was investigated. The effects of striated laser tracks on thermal fatigue resistance were also studied. The results indicated that biomimetic non-smooth surface was benefit for improving thermal fatigue resistance of cast iron sample. The striated non-smooth units formed by laser tracks which were vertical with thermal cracks had the best propagation resistance. The mechanisms behind these influences were discussed, and some schematic drawings were introduced to describe them.

  4. Absorption, emission spectrum properties, and efficient laser performances of Yb:Y3ScAl4O12 ceramics

    International Nuclear Information System (INIS)

    We report on the continuous-wave laser performances of Yb3+-doped disordered Y3Al5O12/Y3Sc2Al4O12 (YAG/YSAG) ceramics fabricated by sintering method. These materials exhibit relatively low minimum pump intensity (Imin) and broad emission bandwidth even in the yttrium aluminum garnet systems. The value of Imin in the Yb:Y3ScAl4O12 ceramics was found to be 2/3 compared with the Yb:YAG single crystal under 970 nm zero-line pumping. Efficient laser oscillation of 72% slope efficiency was obtained for input pump power. These materials attract great interest for high power femtosecond microchip lasers and amplifier applications

  5. Effect of processing parameters on the cohesive strength of laser surface engineered ceramic coatings on aluminum alloys

    International Nuclear Information System (INIS)

    The mechanical performance of laser surface engineered ceramic composite (TiC/Al) coating on 2024 and 6061 Al alloy substrates has been evaluated using four-point bend test. The performance of the coating is expressed in terms of the cohesive strength of the coating. Load-displacement measurements carried out during the bend test helps to determine the load corresponding to crack initiation. This load required to initiate fracture in the coating provides a measure of the strength of the coating. A simplistic approach based on elementary beam theory and strength of material in conjunction with rule of mixture was adopted to calculate the cohesive strength of the composite coating. This approach is also further extended for attempts to evaluate apparent residual stress within the coating. Since process parameters exert a significant influence in controlling the end properties of the component, the effect of laser power and laser scan speed on the cohesive strength has also been investigated. It is observed that coatings with lower scan speeds have much higher cohesive strengths and they also seem to have good metallurgical bond with the substrate thus showing better mechanical behavior than the other high scan speeds used in this present study. The apparent residual stress in the coating appears to transform from compressive to tensile in nature with increasing laser scan speed eventually contributing to delamination of the coating

  6. Laser dressing process of porous cast-iron bonded diamond grinding wheels for machining ceramics

    International Nuclear Information System (INIS)

    Dressing using Yttrium Aluminum Garnet-Second Harmonic Generation (YAG-SHG) laser for porous cast-iron bonded diamond grinding wheels is a unique method. Diamond as an abrasive grain shows transparency with the laser, while cast-iron employed as a bonding and bridging material for the present diamond grinding wheels absorbs it. Hence, it is possible for laser to remove cast-iron selectively with a minimal damage on diamond so that dressing can be optimized. In this investigation a newly proposed dressing process using YAG-SHG laser with the wavelength of 532 nm was conducted upon porous cast-iron bonded diamond grinding wheels with fine grains. It revealed that application of laser for dressing evaporates cast-iron and the amount of evaporation increases with laser flux densities, resulting in an increment of protrusion heights. The wheel dressed with laser allows about six times of removal volume rate on ZrO2 at the maximum rather than the same wheel mechanically dressed. It also achieves 90 times less specific grinding energy. With the increase of laser flux density, the removal volume of ground work pieces can be increased or the specific grinding energy decreased. The laser dressed wheels can also achieve the same surface roughness on ground surfaces as mechanically dressed wheels. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  7. Comparison of Two Kinds of Lasers in the Treatment of Acne Scars.

    Science.gov (United States)

    Reinholz, Markus; Schwaiger, Hannah; Heppt, Markus V; Poetschke, J; Tietze, J; Epple, Andreas; Ruzicka, T; Kaudewitz, P; Gauglitz, Gerd G

    2015-10-01

    Acne scars are common and stigmatizing for the affected patients. Besides surgery, chemical peels, microdermabrasion, and microneedling, the treatment with fractional laser is a standard therapy. The results of reducing acne scars treated either with a fractional Er:YAG (erbium-doped yttrium-aluminum-garnet [Er:Y3Al5O1]) or a carbon dioxide (CO 2 ) laser at different wavelengths were compared and evaluated in the pilot study presented here. Fourteen patients with severe scars on both cheeks were treated four times in a random split-face approach: on one side with Er:YAG laser and on the contralateral side with CO2 laser following a standardized protocol. Therapeutic success was evaluated through the use of a high-resolution, 3D small-field capture system (PRIMOS), digital photography, and the Patient and Observer Scar Assessment Scale (POSAS) questionnaire. The evaluation was performed by a blinded investigator. Treatment results displayed a higher efficacy of the fractional CO2 laser compared with the Er:YAG laser as displayed by digital photographs. Additionally, objective (high-resolution, 3D small-field capture; PRIMOS) and subjective (POSAS) measuring results correlated positively in certain qualities (color, stiffness, thickness, surface, overall opinion). Using a novel scientific approach, we evaluated the therapeutic efficacy of different fractional lasers on acne scars using a rater-blinded approach. Compared with an Er:YAG laser, better skin smoothening was achieved by fractional CO2 laser treatment. PMID:26579867

  8. Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

    Science.gov (United States)

    Haritha, P.; Martín, I. R.; Linganna, K.; Monteseguro, V.; Babu, P.; León-Luis, S. F.; Jayasankar, C. K.; Rodríguez-Mendoza, U. R.; Lavín, V.; Venkatramu, V.

    2014-11-01

    Trivalent dysprosium-doped Lu3Ga5O12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu3Ga5O12 nano-garnets have been studied as a function of the optically active Dy3+ ion concentration and at low temperature. Decay curves for the 4F9/2 level of Dy3+ ion exhibit non-exponential nature for all the Dy3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy3+ concentrations. These results indicate that 2.0 mol% Dy3+ ions doped nano-garnet could be useful for white light emitting device applications.

  9. Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

    International Nuclear Information System (INIS)

    Trivalent dysprosium-doped Lu3Ga5O12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu3Ga5O12 nano-garnets have been studied as a function of the optically active Dy3+ ion concentration and at low temperature. Decay curves for the 4F9/2 level of Dy3+ ion exhibit non-exponential nature for all the Dy3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy3+ concentrations. These results indicate that 2.0 mol% Dy3+ ions doped nano-garnet could be useful for white light emitting device applications

  10. Mechanisms of laser drilling of metal plates underwater

    Science.gov (United States)

    Lu, J.; Xu, R. Q.; Chen, X.; Shen, Z. H.; Ni, X. W.; Zhang, S. Y.; Gao, C. M.

    2004-04-01

    Several metal plates with different thickness including copper, iron, aluminum, and stainless steel have been drilled in the surroundings of air and water, respectively, by a Q-switched pulsed Nd:yttrium-aluminum-garnet laser. It is observed that for the same metal plate less energy is needed to drill a hole in water than that in air, and the surface morphology of hole drilled in water is improved greatly than that in air by comparison of the scanning electron micrographs. The underlying mechanisms behind the efficiency and quality enhancement in water are further investigated by means of optical beam deflection technique. The experimental results show that due to the water confinement the peak amplitude and duration of the laser-ablation-generated impact underwater is much larger than that in air. During the underwater laser drilling, besides laser ablation effect, both the first and second liquid-jet-induced impulses by cavitation bubble collapse in the vicinity of a solid boundary are also observed and their amplitudes are, respectively, about 12.4 and 5.2 times that of the laser ablation impact in air. Cavitation bubbles are the special dynamic phenomenon occurring in liquids. Therefore, it is concluded that in-air-drilling laser ablation-produced impact is a dominant mechanism; while during laser underwater drilling, it is the result of a combination of ablation-produced impact effect and liquid-jet-induced impact, especially the latter. Thus, the efficiency and quality of laser processing in the surrounding water can be greatly increased and improved compared with that in air.

  11. Temperature-dependent nonradiative energy transfer from Gd3+ to Ce3+ ions in co-doped LuAG:Ce,Gd garnet scintillators

    International Nuclear Information System (INIS)

    Energy transfer from donor Gd3+ to acceptor Ce3+ ions was studied in low doped lutetium aluminum garnet, LuAG:Ce,Gd. High purity single crystalline films were prepared by liquid phase epitaxy. The mechanism of nonradiative energy transfer from 6PJ (Gd3+) multiplet to crystal field split 5d2 (2D) states of Ce3+ was established as long-range dipole–dipole interaction and the average critical transfer distance between Gd3+ and Ce3+ ions was found ~14 Å at room temperature. It is shown that the single step energy transfer between donor–acceptor pairs is dominant while migration of excitation energy within the donor Gd3+ subsystem is only a small perturbation in the energy transfer mechanism in the studied low doped garnets. - Highlights: • Photoluminescence and decay kinetics in co-doped LuAG:Ce,Gd garnets. • Energy transfer from Gd3+ to Ce3+ in LuAG:Ce,Gd garnets. • Ce doped multicomponent garnet scintillators

  12. Temperature-dependent nonradiative energy transfer from Gd{sup 3+} to Ce{sup 3+} ions in co-doped LuAG:Ce,Gd garnet scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Onderisinova, Z. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Kucera, M., E-mail: kucera@karlov.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Hanus, M. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Nikl, M. [Institute of Physics, AS CR, Cukrovarnicka 10, 162 00 Prague 6 (Czech Republic)

    2015-11-15

    Energy transfer from donor Gd{sup 3+} to acceptor Ce{sup 3+} ions was studied in low doped lutetium aluminum garnet, LuAG:Ce,Gd. High purity single crystalline films were prepared by liquid phase epitaxy. The mechanism of nonradiative energy transfer from {sup 6}P{sub J} (Gd{sup 3+}) multiplet to crystal field split 5d{sub 2} ({sup 2}D) states of Ce{sup 3+} was established as long-range dipole–dipole interaction and the average critical transfer distance between Gd{sup 3+} and Ce{sup 3+} ions was found ~14 Å at room temperature. It is shown that the single step energy transfer between donor–acceptor pairs is dominant while migration of excitation energy within the donor Gd{sup 3+} subsystem is only a small perturbation in the energy transfer mechanism in the studied low doped garnets. - Highlights: • Photoluminescence and decay kinetics in co-doped LuAG:Ce,Gd garnets. • Energy transfer from Gd{sup 3+} to Ce{sup 3+} in LuAG:Ce,Gd garnets. • Ce doped multicomponent garnet scintillators.

  13. Holmium:YAG surgical lasers.

    Science.gov (United States)

    1995-03-01

    "Holmium:YAG (Ho:YAG)" is the shorthand name for a family of solid-state lasers that use the doping element holmium in a laser crystal (e.g., YAG [yttrium-aluminum-garnet]) and that emit energy at approximately 2.1 microns. This wavelength is relatively new to medicine and has been used in laser surgery for only about the last six years. Like the carbon dioxide (CO2) laser when it was first used clinically, the Ho:YAG laser is poised for rapid and wide-spread use. Ho:YAG lasers, like CO2 lasers, offer precise cutting with minimal damage to adjacent tissue; however, unlike CO2 lasers, they also offer fiberoptic delivery (which is ideal for endoscopic use) and the ability to treat tissue in a liquid-filled environment (e.g., saline, blood). The initial specialty for which the Ho:YAG laser was used was arthroscopic surgery, especially diskectomy. Today, it is effectively used in many surgical specialties, including general surgery, urology, laparoscopy, neurosurgery, lithotripsy, angioplasty, orthopedic surgery (which includes procedures such as meniscectomy, bone sculpting [may also be performed in plastic surgery], and some experimental surgery, such as cartilage shrinking to tighten loose joints), and dentistry. Because of its broad range of potential applications, it has been called the "Swiss Army Knife" of lasers. High-powered Ho:YAG lasers, which enable surgeons to work more quickly and cut more smoothly, have been made available only within the last three years (units offering > 20 W) to 18 months (units offering > 60 W). Because of this rapid increase, high-powered units are still relatively expensive, and it is not yet clear whether maximum power outputs will continue to increase or whether the cost of higher-power units will begin to come down. Although low-power and high-power Ho:YAG lasers can be used for the same procedures, their different ranges of possible clinical techniques make them better suited to different applications: low-power units are

  14. Analysis of Temperature and Residual Stress Distribution in CO2 Laser Welded Aluminum 6061 Plates Using FEM

    Directory of Open Access Journals (Sweden)

    Sanaa Numan Mohammed

    2011-01-01

    Full Text Available This paper develops a nonlinear transient three-dimensional heat transfer finite element model and a rate independent three-dimensional deformation model, developed for the CO2 laser welding simulations in Al-6061-T6 alloy. Simulations are performed using an indirect coupled thermal-structural method for the process of welding. Temperature-dependent thermal properties of Al-6061-T6, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. The heat input to the model is assumed to be a Gaussian heat source. The finite element code ANSYS12, along with a few FORTRAN subroutines, are employed to obtain the numerical results. The benefit of the proposed methodology is that it offers the capability of optimizing laser welding process, and also provides a reliable estimation of the developed temperatures, as well as the thermal stress (residual stress and strain fields reducing the experimental effort.

  15. Pilot study: intravenous use of indocyanine green as an enhancer for 808-nm diode laser application in the equine

    Science.gov (United States)

    Tate, Lloyd P.; Blikslager, Anthony T.; Papich, Mark G.

    2000-05-01

    The 808-nm diode laser, delivering 20 - 40 watts of power, has been produced for medical applications by several manufacturers over the past 10 years. This laser's power output is less than most Neodymium:yttrium aluminum garnet (Nd:YAG) lasers and other high power cutting lasers that use fiberoptic delivery systems. The 808-nm diode laser has not gained popularity in equine transendoscopic laser surgery. Indocyanine green (ICG) is absorbed at 810-nm of light which when concentrated in tissue should be an excellent absorber for the energy produced by the 808-nm diode laser. This study compares the depths and widths of penetration achieved with the 808-nm diode laser after intravenous injection of ICG in equine respiratory tissue. Indocyanine green was administered at two doses: 1.5 mg/kg and 3 mg/kg. The 808-nm diode laser was set to deliver 200 joules of energy. The depths and widths of penetration were also compared to the Nd:YAG laser applied at the same energy setting.

  16. Development of a technology for laser welding of the 1424 aluminum alloy with a high strength of the welded joint

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-11-01

    Results of an experimental study of properties of joints obtained by using different regimes of laser welding of the 1424 alloy (Al-Mg-Li) are reported. The strength and structure of the welded joints are determined. The influence of various types of welded joint straining on its strength is studied. It is demonstrated that the joint strength increases in the case of plastic straining.

  17. Saturable absorption of an X-ray free-electron-laser heated solid-density aluminum plasma

    Czech Academy of Sciences Publication Activity Database

    Rackstraw, D.S.; Ciricosta, O.; Vinko, S.M.; Barbrel, B.; Burian, Tomáš; Chalupský, Jaromír; Cho, B.I.; Chung, H.-K.; Dakovski, G.L.; Engelhorn, K.; Hájková, Věra; Heimann, P.; Holmes, M.; Juha, Libor; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J.J.; Zastrau, U.; Wark, J. S.

    2015-01-01

    Roč. 114, č. 1 (2015), "015003-1"-"015003-5". ISSN 0031-9007 R&D Projects: GA ČR(CZ) GA14-29772S; GA MŠk(CZ) LG13029 Grant ostatní: AVČR(CZ) M100101221 Institutional support: RVO:68378271 Keywords : free electron laser * x-ray * ionization of plasmas Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 7.512, year: 2014

  18. Simultaneous effects of external electric field and aluminum concentration on the binding energy of a laser-dressed donor impurity in a spherical quantum dot confined at the center of a cylindrical nano-wire

    International Nuclear Information System (INIS)

    Based on the effective-mass approximation, the effects of external electric field and laser radiation on the binding energy and Stark shifts of electronic energy levels of a system consist of an on-center hydrogenic donor impurity in a spherical quantum dot which is located at the center of a cylindrical nano-wire have been studied. The energy eigenvalues and corresponding wave functions are calculated using the finite difference approximation. The binding energy and Stark shifts dependencies are reported upon the electric field strength, aluminum concentration and laser radiation. The results reveal that Stark shifts of ground and first excited states are strongly affected by presence of impurity, laser radiation and Al concentration. Additionally, the binding energies decreases as the electric field increases and become negligible for large values of electric field; decreases as the laser radiation increases and increases as the Al concentration increases

  19. Nonlinear FMR spectra in yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

    2015-12-01

    Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

  20. On the Crystallization of Terbium Aluminium Garnet

    OpenAIRE

    Ganschow, S.; Klimm, D.; Reiche, P.; Uecker, R.

    2008-01-01

    Attempts to grow terbium aluminium garnet (Tb3Al5O12, TAG) by the Czochralski method lead to crystals of millimeter scale. Larger crystals could not be obtained. DTA measurements within the binary system showed that TAG melts incongruently at 1840 deg. C. The perovskite (TbAlO3, TAP) with a congruent melting point of 1930 deg. C is the most stable phase in this system. The region for primary crystallization of TAP covers the chemical composition of TAG and suppresses the primary crystallizati...

  1. Development and application investigation of an ICSHG 532 nm diode-pumped solid-state laser system

    Science.gov (United States)

    Nhat Khoa Phan, Thanh; Tu, Trung Chan; Thuat Nguyen, Tran; Chien Nguyen, Thanh; Chien Dang, Mau

    2011-12-01

    A diode-pump solid-state laser system emitting a 532 nm beam has been developed. The pump source is an 808 nm diode laser, which has gained wide acceptance in research as well as in commercial production due to its effectiveness and reasonable price. The active medium was chosen to be Nd:YVO4 (neodymium-doped yttrium orthovanadate), a material with many advantages over traditional Nd:YAG (neodymium-doped yttrium aluminum garnet) such as a low lasing threshold and linearly polarized beam. However, the thermal conductivity of Nd:YVO4 is not as good as Nd:YAG, thus the thermal lens effect inside Nd:YVO4 under high pumping intensity becomes severe and detrimental to the laser performance. Our work showed that careful adjustments of Nd:YVO4 temperature as well as of the cavity's parameters played an important role in the performance of the laser. Potassium titanyl phosphate (KTP), a nonlinear optics crystal, was used to convert the fundamental 1064 nm laser radiation from Nd:YVO4 into 532 nm. The 532 nm laser beam has been successfully proven to cut wood, plastic and aluminum.

  2. Laser Systems For Use With Airborne Platforms

    Science.gov (United States)

    Jepsky, Joseph

    1984-10-01

    This paper describes a family of airborne laser systems in use for terrain profiling, surveying, mapping, altimetry, collision avoidance and shipboard landing systems using fixed and rotary wing aircraft as the platforms. The laser altimeter has also been used in systems compatible with the Army T-16 and. T-22 carrier missiles (platform). Both pulsed gallium arsenide and Nd:YAG (neodymium-doped, yttrium-aluminum-garnet) laser rangefinders have been used for these applications. All of these systems use ACCI's advanced measurement techniques that permit range accuracies of 8 cm, single shot, 1 cm averaged, to be achieved. Pulse rates up to 4 Khz are employed for airborne profiling. This high data density rate provides 1 data point every 2" along the aircraft flight line at aircraft speed of 500 knots. Scanning modes for some applications are employed. Systems have been integrated with all current inertial navigation systems (Litton, Ferranti and Honeywell), as well as a number of microwave positioning systems. Removal of aircraft motion from the laser range measurements by use of an accelerometer is described. Flight data from a number of program performed by U.S. and Canadian Federal Agencies, in addition to those of commercial surveying and mapping companies are described.

  3. 1.8kW laser diode pumped YAG laser; Shutsuryoku 1.8kW no handotai laser reiki YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Toshiba Corporation, as a participant in Ministry of International Trade and Industry`s `photon measurement and processing technology project` since August, 1997, is engaged in the development of an energy-efficient LD (laser diode) pumped semiconductor YAG (yttrium-aluminum-garnet) laser device to be used for welding and cutting. It is a 5-year project and the goal is a mean output of 10kW and efficiency of 20%. In this article, a simulation program is developed which carries out calculation about element technology items such as the tracking of the beam from the pumping LD and the excitation distribution, temperature distribution, thermal stress distribution, etc., in the YAG rod. An oscillator is constructed, based on the results of the simulation, and it exhibits a world-high class continuous laser performance of a 1.8kW output and 13% efficiency. The record of 13% efficiency is five times higher than that achieved by the conventional lamp-driven YAG laser device. (translated by NEDO)

  4. Experimental demonstration of a dual-frequency laser free from anti-phase noise

    CERN Document Server

    Amili, Abdelkrim El; De, Syamsundar; Schwartz, Sylvain; Feugnet, Gilles; Pocholle, Jean-Paul; Bretenaker, Fabien; Alouini, Mehdi

    2012-01-01

    A reduction of more than 20 dB of the intensity noise at the anti-phase relaxation oscillation frequency is experimentally demonstrated in a two-polarization dual-frequency solid-state laser without any optical or electronic feedback loop. Such a behavior is inherently obtained by aligning the two orthogonally polarized oscillating modes with the crystallographic axes of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The anti-phase noise level is shown to increase as soon as one departs from this peculiar configuration, evidencing the predominant role of the nonlinear coupling constant. This experimental demonstration opens new perspectives on the design and realization of extremely low noise dual-frequency solid-state lasers.

  5. On the plume splitting of pulsed laser ablated Fe and Al plasmas

    International Nuclear Information System (INIS)

    A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd:YAG (yttrium aluminum garnet) laser operating at 532 nm with a pulse duration of ∼8 ns full width at half maximum and a fluence of 30 Jcm-2 at the target surface. Typical time resolved images with low magnification show that the splitting occurs at moderate background gas pressures (0.5 and 1.0 mbar for Fe, and 0.2 mbar for Al plasma plumes). The plume splitting did not occur for higher background gas pressures.

  6. On the plume splitting of pulsed laser ablated Fe and Al plasmas

    Science.gov (United States)

    Mahmood, S.; Rawat, R. S.; Darby, M. S. B.; Zakaullah, M.; Springham, S. V.; Tan, T. L.; Lee, P.

    2010-10-01

    A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd:YAG (yttrium aluminum garnet) laser operating at 532 nm with a pulse duration of ˜8 ns full width at half maximum and a fluence of 30 Jcm-2 at the target surface. Typical time resolved images with low magnification show that the splitting occurs at moderate background gas pressures (0.5 and 1.0 mbar for Fe, and 0.2 mbar for Al plasma plumes). The plume splitting did not occur for higher background gas pressures.

  7. Stoichiometric analysis of compositionally graded combinatorial amorphous thin film oxides using laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy (LIBS) is a recently developed locally destructive elemental analysis technique that can be used to analyze solid, liquid, and gaseous samples. In the system explored here, a neodymium-doped yttrium aluminum garnet laser ablates a small amount of the sample and spectral emission from the plume is analyzed using a set of synchronized spectrometers. We explore the use of LIBS to map the stoichiometry of compositionally graded amorphous indium zinc oxide thin-film libraries. After optimization of the experimental parameters (distance between lens and samples, spot size on the samples, etc.), the LIBS system was calibrated against inductively coupled plasma atomic emission spectroscopy which resulted in a very consistent LIBS-based elemental analysis. Various parameters that need to be watched closely in order to produce consistent results are discussed. We also compare LIBS and x-ray fluorescence as techniques for the compositional mapping of libraries.

  8. Formation of cobalt/garnet heterostructures and their magnetic properties

    International Nuclear Information System (INIS)

    In this paper we report the use of ion beam sputtering to form Co/garnet heterostructures with a sub-nanometer roughness parameter at the interface. Prior to the ultrathin Co layer deposition, garnet films are thinned to a thickness range of 6.5 μm to 1 μm by oxygen ion beam sputtering with a low energy regime. The magnetic properties and magnetic anisotropy of the Co/garnet heterostructures are measured by both magneto-optical magnetometry and ferromagnetic resonance. We have shown that Gilbert damping of the Co layers on the garnet films is comparable to the damping of single layer polycrystalline Co grown on metallic under-layers. - Highlights: • We report a damage-free method for surface modification in garnets. • Tuning the garnet thickness by etching using ion beam sputtering • We measured the magnetic anisotropy in Co/garnet heterostructures. • Gilbert damping in the Co films on a garnet films was obtained

  9. Magneto-optic eddy current introscopy based on garnet films

    OpenAIRE

    Vishnevskii, V.; Berzhansky, V.; Mikhailov, V.; Pankov, F.; Nedviga, A.; Nesteruk, A

    2012-01-01

    Magneto-optic eddy current introscopy device based on garnet films with stroboscopic illumination is described. Experiment was done with liquid-phase epitaxy garnet films with composition (Bi,Eu,Lu)3(Fe,Ga,Al)5O12 and (Bi,Tm)3(Fe,Ga)5O12; crystallographic orientation (111).

  10. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates are simi...

  11. Garnet and pyroxene compositions in some diamondiferous eclogites

    Science.gov (United States)

    Reid, A. M.; Brown, R. W.; Dawson, J. B.; Whitfield, G. G.; Siebert, J. C.

    1976-01-01

    Analyses are reported for garnet and pyroxene from 17 eclogites that contain diamond. The garnets contain small but significant contents of Na, Ti and P and the pyroxenes contain traces of K. The diamond-bearing eclogites do not constitute a unique compositional group but show a range of mineral compositions consistent with a very high P-T environment.

  12. Magneto-optical study of holmium iron garnet Ho3Fe5O12

    International Nuclear Information System (INIS)

    Bulk holmium iron garnet Ho3Fe5O12 is a cubic ferrimagnet with Curie temperature Tc = 567 K and magnetization compensation point between 130-140 K. The magneto-optical data are presented for a holmium iron garnet Ho3Fe5O12 epitaxial approx 10 mkm thick film grown on a (111)-type gadolinium-gallium garnet Gd3Ga5O12 substrate. A specific feature of this structure is the closeness of the parameters of the bulk material, from which the film has been grown, to the substrate ones. Temperature and field dependences of the Faraday effect and temperature dependence of the domain structure in zero field are investigated. The compensation point of the structure is found to be Tcomp = 127 K. It is shown that the temperature dependence of characteristic size of the domain structure diverges at this point. It is established that the magnetic anisotropy of the material is determined by both uniaxial and cubic contributions, each being characterized by different temperature dependence. A complex form of hysteresis loops and a sharp changes of the domain pattern with varying temperature suggest that there occur collinear-noncollinear phase transitions. Study of the optical second harmonic generation was carried out using 100 fs laser pulses with central photon energy E = 1,55 eV. The electric dipole contribution (both crystallographic and magnetic) to the second harmonic generation was observed with high reliability despite a small mismatch of the film and substrate parameters.

  13. Growth features of rare-earth scandium garnets

    International Nuclear Information System (INIS)

    The growth features of rare-earth scandium garnets (RESG) are closely connected with peculiarities of the nature of scandium garnets. The speciality of RESG first of all consists in complex scandium isomorphism, which is connected with redistribution of Sc3+ on sublattices of the garnet structure. The scandium isomorphism in RESG considerably influences the crystal growth, since scandium garnets possess a wide range of homogeneity at rather flat liquids. The presence of chromium ions in RESG strongly increases the absorption capability of the medium and leads to the rise of interface instability during the growth. The principal differences between ScGa- and ScAl-garnets concerning crystallization features are considered. (author). 38 refs., 2 figs

  14. Nanocrystalline gadolinium iron garnet for circulator applications

    International Nuclear Information System (INIS)

    Due to high resistivity and low microwave losses, gadolinium iron garnets (GdIG) are useful materials for non-reciprocal devices such as circulators or isolators. Keeping the miniaturization and cost reduction in mind, the trend is to modify the conventional methods of preparation of samples. In this connection we have synthesized nanocystalline GdIG by using the Microwave Hydrothermal method at 160 °C/45 min. As synthesized powders were characterized by using X-ray diffraction (XRD), transmission electron microscopy and Fourier Transform Infrared Spectroscopy. XRD patterns show the formation of a garnet phase with crystallite size varying between 19 nm and 40 nm. Differential Thermal Analysis studies were also carried out on the nanopowders. The powders were densified at a lower sintering temperature of 1100 °C/45 min using a microwave sintering method. The sintered samples were characterized by XRD and atomic force microscopy. The frequency dependence of complex permittivity and ferromagnetic resonance were measured in the Ka band frequency (27–40 GHz). Magnetic properties were also measured at room temperature. - Highlights: ► GdIG ferrites were synthesized using the microwave hydrothermal method. ► Densification of the GdIG samples was done at a low temperature of 1100 °C/45 min. ► Our samples possess low dielectric constant and loss at a Ka band frequency. ► Nanocrystalline GdIG samples for circulator application have been tested.

  15. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

    Directory of Open Access Journals (Sweden)

    Y Al-Hadeethi

    Full Text Available Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM. Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX. The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.

  16. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation

    Science.gov (United States)

    Abdel-Daiem, A. M.; Ansari, M. Shahnawaze; Babkair, Saeed S.; Salah, Numan A.; Al-Mujtaba, A.

    2016-01-01

    Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased. PMID:27228169

  17. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

    Science.gov (United States)

    Al-Hadeethi, Y; Al-Jedani, S; Razvi, M A N; Saeed, A; Abdel-Daiem, A M; Ansari, M Shahnawaze; Babkair, Saeed S; Salah, Numan A; Al-Mujtaba, A

    2016-01-01

    Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased. PMID:27228169

  18. Oxygen isotope zonation of a single garnet from UHPM calcsilicate rock of Kokchetav Massif, Kazakhstan: a window into the geochemical nature of deeply subducted crustal rocks

    Science.gov (United States)

    Sobolev, N. V.; Schertl, H.; Valley, J. W.; Page, F.; Kita, N.; Spicuzza, M.; Neuser, R. D.; Logvinova, A. M.

    2009-12-01

    Calcsilicates (dolomite marbles) and garnet-pyroxene rocks with Mg-calcite matrix represent the most unusual rock types within dominant UHPM diamondiferous biotite gneisses and schists of the Kokchetav Massif. They are characterized by extremely high diamond grade (up to 3,000 carats per metric ton) and an unusual assemblage of very high Mg-garnet (Mg# up to 93.7) with varied Ca-numbers (42.5 - 66.5) and K-bearing diopside. A calcsilicate sample with alternating layers showing different lithologies with considerable amounts of garnet and clinopyroxene in dolomite or Mg-calcite matrix was selected for careful oxygen isotope and EPMA study of garnets and pyroxenes. A grain of fresh garnet with a luminescent core indicating very low iron contents (Mg# 92.6 - 93.7) and a non-luminescent part (Mg# 87.1 - 88.2) was selected for the study of δ18O with a CAMECA IMS-1280 ion probe (10 micron spot). No cracks were found within the selected layered sample, which is a “micro-outcrop” of several rock types at cm-scale. In parts, a symplectite composed of pyroxene and spinel is developed around studied garnet. A significant difference in δ18O between 12.9 - 13.5‰ VSMOW for high Mg luminescent core and 11.9 - 12.6 for non-luminescent overgrowth was found. Additional separates of hand-picked garnet and clinopyroxene grains from different parts of the same 0.1 kg-size sample fragment (selected by color differences) were analyzed for δ18O by laser fluorination at mm-scale. Values of δ18O measured in this work vary between 6.25 and 10.63, demonstrating δ18O-gradients of over 7‰ in garnets over distances of less than 2 cm. Thus oxygen isotopic ratios of garnets and clinopyroxenes of one hand specimen are heterogeneous and even can vary within single crystals. The δ18O values for the garnets analyzed here belong to the highest observed for UHP-origin (both for metamorphic rocks and for kimberlites). The unusual zonation in δ18O within mineral grains of the same species

  19. Thermal expansion in the garnet-type solid electrolyte (Li7−xAlx/3)La3Zr2O12 as a function of Al content

    International Nuclear Information System (INIS)

    Highlights: • Thermal expansion (TE) coefficients of LLZ found up to 700°. • The aluminum content of LLZ has a small impact on the thermal expansion. • Typical thermal expansion values were around, 16 × 10−6 K−1. • The TE is approximately double other garnet-type structures. - Abstract: The thermal expansion (TE) coefficients of the lithium-stable lithium-ion conducting garnet lithium lanthanum zirconium oxide (LLZ) and the effect of aluminum substitution were measured from room temperature up to 700 °C by a synchrotron-based X-ray diffraction. The typical TE value measured for the most reported composition (LLZ doped with 0.3 wt.% or 0.093 mol% aluminum) was 15.498 × 10−6 K−1, which is approximately twice the value reported for other garnet-type structures. As the Al(III) concentration has been observed to strongly affect the structure observed and the ionic conductivity, we also assessed its role on thermal expansion and noted only a small variation with increasing dopant concentration. The materials implications for using LLZ in a solid state battery are discussed

  20. SEM evaluation of the morphological changes in hard dental tissues prepared by Er: YAG laser and rotary instruments

    Directory of Open Access Journals (Sweden)

    Tomov Georgi

    2010-09-01

    Full Text Available Effective ablation of dental hard tissues by means of the erbium:yttrium-aluminum garnet (Er: YAG laser has been reported recently, and its application to caries removal and cavity preparation has been expected. However, few studies have investigated the morphological changes in hard dental tissues after Er: YAG laser caries treatment. In the present study the morphological changes in hard dental tissues after Er: YAG laser caries ablation in vitro was compared with that of conventional mechanical treatment. Thirty extracted human teeth with caries were used. Ten tooth was treated with the Er: YAG laser, and the other was treated with a conventional steel and diamond burs. Laser treatment was performed by means of a non-contact irradiation modes with cooling water spray, with a new Er: YAG laser (LiteTouch. Conventional bur treatment was conducted by means of a low-speed micromotor and air turbine with water cooling. Scanning electron microscope (SEM observations were performed for each treatment. The Er: YAG laser ablated carious dentin effectively with minimal thermal damage to the surrounding intact dentin, and removed infected and softened carious dentin to the same degree as the burtreatment. In addition, a lower degree of vibration was noted with the Er: YAG laser treatment. The SEM examination revealed characteristic micro-irregularities of the lased dentin and enamel surfaces with potential benefits for adhesive restorations. Our results show that the Er: YAG laser is promising as a new technical modality for caries treatment

  1. Effect of the Pr.sup.3+./sup.→Gd.sup.3+./sup. energy transfer in multicomponent garnet single crystal scintillators

    Czech Academy of Sciences Publication Activity Database

    Babin, Vladimir; Nikl, Martin; Kamada, K.; Beitlerová, Alena; Yoshikawa, A.

    2013-01-01

    Roč. 46, č. 36 (2013), s. 1-6. ISSN 0022-3727 R&D Projects: GA MŠk LH12150 Institutional support: RVO:68378271 Keywords : scintillator * Pr 3+ * garnet * energy transfer * decay kinetics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.521, year: 2013 http://stacks.iop.org/JPhysD/46/365303

  2. Daughter minerals in fluid inclusions of garnet and diopside from Tongguanshan Copper Deposit by SEM/EDS and LRM

    Institute of Scientific and Technical Information of China (English)

    Yuling Xie; Jiuhua Xu; Zengqian Hou; Zhusen Yang; Wenyi Xu; Yifeng Meng; Baohua Wang

    2004-01-01

    Tongguanshan copper deposit of Tongling large ore belt is one of the typical skarn copper deposits. Based on careful observation under microscope many daughter minerals including transparent ones and opaque ones have been distinguished in the fluid inclusions of garnet and diopside. The results of SEM/EDS (scanning electron microscope/energy dispersive spectrometer) and LRM (laser Raman microprobe) analysis show that these daughter minerals in garnet are sylvite, halite, sphalerite, chalcopyrite and carbonate. Sylvite daughter mineral is very popular in garnet and diopside. The existence of so much sylvite daughter mineral and other daughter minerals in the fluid inclusions indicates that the ore-forming fluid is of supper-high salinity and high potassium concentration. High potassium concentration in the fluid inclusions agrees with K-rich mesotype-acid rock and K-silicate alteration that occurred widely in this area. The daughter mineral assemblage in garnet and diopside is similar to the mineral assemblage of oreforming stage that followed skarn stage.

  3. Geothermobarometric history of subduction recorded by quartz inclusions in garnet

    Science.gov (United States)

    Ashley, Kyle T.; Caddick, Mark J.; Steele-MacInnis, Matthew J.; Bodnar, Robert J.; Dragovic, Besim

    2014-02-01

    Burial histories of subduction zone rocks are often difficult to accurately constrain, owing to a lack of robust mineral geobarometers applicable to high pressure mineral assemblages. Knowledge of the depth-histories of subduction is, however, required for our understanding of global geochemical cycles, subduction-related seismicity, and the evolution of destructive tectonic boundaries. The high spatial resolution of quartz inclusion geobarometry can be used to determine pressure evolution during metamorphic growth of individual garnet crystals. Quartz inclusions in garnet from Sifnos, Greece, preserve such a record of the pressure of garnet growth, allowing detailed reconstruction of the metamorphic evolution of these rocks. Pressure-dependent Raman spectra of quartz inclusions were combined with elastic modeling to infer the conditions at which they were trapped during garnet growth. All measured inclusions suggest that garnet growth occurred between 19 and 20.5 kbars, with little evidence for significant pressure variation during the garnet growth interval, which is interpreted to record ˜100°C of heating. Coupled with thermometry and geochronology, these results show that early, cold burial was followed by a phase of rapid heating, which immediately preceded exhumation. Garnet growth occurred primarily during this heating phase.

  4. Garnet peridotites from Pohorje: Petrography, geothermobarometry and metamorphic evolution

    Directory of Open Access Journals (Sweden)

    Mirijam Vrabec

    2010-06-01

    Full Text Available Ultrahigh-pressure (UHP metamorphism has been recorded in Eo-Alpine garnet peridotites from the PohorjeMts., Slovenia, belonging to the Eastern Alps. The garnet peridotite bodies are found within serpentinized metaultrabasitesin the SE edge of Pohorje and are closely associated with UHP kyanite eclogites. These rocks belongto the Lower Central Austroalpine basement unit of the Eastern Alps, exposed in the proximity of the Periadriaticfault system.Garnet peridotites show signs of a complex four-stage metamorphic history. The protolith stage is represented bya low-P high-T assemblage of olivine + Al-rich orthopyroxene + Al-rich clinopyroxene + Cr-spinel. Due to metamorphism,primary clinopyroxene shows exsolutions of garnet, orthopyroxene, amphibole, Cr-spinel and ilmenite. TheUHP metamorphic stage is defined by the assemblage garnet + olivine + Al-poor orthopyroxene + clinopyroxene +Cr-spinel. Subsequent decompression and final retrogression stage resulted in formation of kelyphitic rims aroundgarnet and crystallization of tremolite, chlorite, serpentine and talc.Pressure and temperature estimates indicate that garnet peridotites reached the peak of metamorphism at 4 GPaand 900 °C, that is well within the UHP stability field. Garnet peridotites in the Pohorje Mountains experiencedUHP metamorphism during the Cretaceous orogeny and thus record the highest-pressure conditions of all Eo-Alpinemetamorphism in the Alps.

  5. Ion irradiation effects in natural garnets: Comparison with zircon

    International Nuclear Information System (INIS)

    The behavior of garnet (A3B2(XO4)3; Ia3d; Z=8) under ion-beam irradiation was investigated in order to compare its radiation susceptibility to another orthosilicate: zircon, ZrSiO4. Five natural end-member compositions were examined by in situ transmission electron microscopy during irradiation with 1.0 MeV Kr2+ over the temperature range of 50-1070 K. The critical amorphization temperature, above which amorphization does not occur, was 1030 K for andradite, but could not be determined for the other garnet composition because the Tc was higher than the highest temperature of the experiment. Based on topologic criterion, the degree of structural freedom in garnet is ∼-2.25 and for zircon ∼-1.5. Based on topology the critical amorphization dose for garnet should be higher than that of zircon; however, the average amorphization dose of garnet (0.20 dpa) is lower than that of zircon (0.37 dpa) at room temperature. This may be the result of the assumed value for the displacement energies, Ed, used in the calculation of dpa. Garnet did not decompose, while zircon decomposes to SiO2+ZrO2 during the ion irradiation at high temperature. This behavior may be related to the phase relations of garnet which melts congruently and zircon which decomposes to ZrO2+SiO2

  6. Efficient and stable laser-driven white lighting

    Directory of Open Access Journals (Sweden)

    Kristin A. Denault

    2013-07-01

    Full Text Available Laser-based white lighting offers a viable option as an efficient and color-stable high-power solid-state white light source. We show that white light generation is possible using blue or near-UV laser diodes in combination with yellow-emitting cerium-substituted yttrium aluminum garnet (YAG:Ce or a mixture of red-, green-, and blue-emitting phosphors. A variety of correlated color temperatures (CCT are achieved, ranging from cool white light with a CCT of 4400 K using a blue laser diode to a warm white light with a CCT of 2700 K using a near-UV laser diode, with respective color rendering indices of 57 and 95. The luminous flux of these devices are measured to be 252 lm and 53 lm with luminous efficacies of 76 lm/W and 19 lm/W, respectively. An estimation of the maximum efficacy of a device comprising a blue laser diode in combination with YAG:Ce is calculated and the results are used to optimize the device.

  7. Photodynamic therapy of murine non-melanoma skin carcinomas with diode laser after topical application of aluminum phthalocyanine chloride

    Science.gov (United States)

    Kyriazi, Maria; Alexandratou, Eleni; Yova, Dido; Rallis, Michail; Trebst, Tilmann

    2007-07-01

    The aim of this work is to study pharmacokinetics and photodynamic efficiency of aluminium phthalocyanine chloride (AlClPc) in dimethylsulfoxide/Tween 80/water solution, after topical application on hairless mice bearing non-melanoma skin carcinomas. The concentration of photosensitizer in normal skin and tumor biopsies 1-6 hours after application was assessed by fluorescence spectroscopy of chemical extractions. The concentration of photosensitizer was 40 times higher in tumor than in normal skin even 1 h after application. For photodynamic therapy (PDT) AlClPc was excited by a diode laser emitting at 670 nm, 1 h after application. Seven different combinations of therapeutic parameters were chosen. The efficiency was assessed as the percentage of complete tumor remission, the tumor growth retardation and the cosmetic outcomes. The highest complete remission 60% was achieved with the combination of 75 mW/cm2 with 150 J/cm2. No recurrence rate was observed in any treatment parameters group and the cosmetic outcome in all completely treated tumors was excellent. The results show that the effectiveness of PDT is highly dependent on fluence rate. In addition, they are promising for further investigation of this PDT scheme in preclinical studies mainly in non-melanoma skin carcinomas up to 7mm.

  8. Yttrium aluminium garnet under pressure: Structural, elastic, and vibrational properties from ab initio studies

    Energy Technology Data Exchange (ETDEWEB)

    Monteseguro, V. [Departamento de Física and MALTA Consolider Team, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Rodríguez-Hernández, P.; Muñoz, A., E-mail: amunoz@ull.es [Departamento de Física and MALTA Consolider Team, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Instituto de Materiales y Nanotecnología. Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain)

    2015-12-28

    The structural, elastic, and vibrational properties of yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12} are studied under high pressure by ab initio calculations in the framework of the density functional theory. The calculated ground state properties are in good agreement with the available experimental data. Pressure dependences of bond length and bulk moduli of the constituent polyhedra are reported. The evolution of the elastic constants and the major elastic properties, Young and shear modulus, Poisson's ratios, and Zener anisotropy ratio, are described. The mechanical stability is analyzed, on the light of “Born generalized stability criteria,” showing that the garnet is mechanically unstable above 116 GPa. Symmetries, frequencies, and pressure coefficients of the Raman-active modes are discussed on the basis of the calculated total and partial phonon density of states, which reflect the dynamical contribution of each atom. The relations between the phonon modes of Y{sub 3}Al{sub 5}O{sub 12} and the internal and external molecular modes of the different polyhedra are discussed. Infrared-active modes, as well as the silent modes, and their pressure dependence are also investigated. No dynamical instabilities were found below 116 GPa.

  9. Antiphase state in passively Q-switched Yb:YAG microchip multimode lasers with a saturable absorber GaAs

    International Nuclear Information System (INIS)

    We report on recent experimental results of the spontaneous antiphase dynamics that occurs in a laser-diode-pumped multimode passively Q-switched microchip Yb:YAG (where YAG is yttrium aluminum garnet) lasers with a saturable absorber GaAs. We observe that the pulse sequence of the first mode characterized by one, two, and three pulses as a group and all the modes display an antiphase state as the pumping ratio rises. We modify the multimode rate equations to account for nonlinear absorption due to GaAs in the presence of spatial hole burning. We perform numerical simulations based on the proposed rate equations and reproduce the observed antiphase state of two and three active modes

  10. Laser-induced breakdown spectroscopy for in-cylinder equivalence ratio measurements in laser-ignited natural gas engines.

    Science.gov (United States)

    Joshi, Sachin; Olsen, Daniel B; Dumitrescu, Cosmin; Puzinauskas, Paulius V; Yalin, Azer P

    2009-05-01

    In this contribution we present the first demonstration of simultaneous use of laser sparks for engine ignition and laser-induced breakdown spectroscopy (LIBS) measurements of in-cylinder equivalence ratios. A 1064 nm neodynium yttrium aluminum garnet (Nd:YAG) laser beam is used with an optical spark plug to ignite a single cylinder natural gas engine. The optical emission from the combustion initiating laser spark is collected through the optical spark plug and cycle-by-cycle spectra are analyzed for H(alpha)(656 nm), O(777 nm), and N(742 nm, 744 nm, and 746 nm) neutral atomic lines. The line area ratios of H(alpha)/O(777), H(alpha)/N(746), and H(alpha)/N(tot) (where N(tot) is the sum of areas of the aforementioned N lines) are correlated with equivalence ratios measured by a wide band universal exhaust gas oxygen (UEGO) sensor. Experiments are performed for input laser energy levels of 21 mJ and 26 mJ, compression ratios of 9 and 11, and equivalence ratios between 0.6 and 0.95. The results show a linear correlation (R(2) > 0.99) of line intensity ratio with equivalence ratio, thereby suggesting an engine diagnostic method for cylinder resolved equivalence ratio measurements. PMID:19470212

  11. Thermochromism in yttrium iron garnet compounds.

    Science.gov (United States)

    Serier-Brault, Hélène; Thibault, Lucile; Legrain, Magalie; Deniard, Philippe; Rocquefelte, Xavier; Leone, Philippe; Perillon, Jean-Luc; Le Bris, Stéphanie; Waku, Jean; Jobic, Stéphane

    2014-12-01

    Polycrystalline yttrium iron garnet (Y3Fe5O12, hereafter labeled YIG) has been synthesized by solid-state reaction, characterized by X-ray diffraction, Mössbauer spectroscopy, and UV-vis-NIR diffuse reflectance spectroscopy, and its optical properties from room temperature (RT) to 300 °C are discussed. Namely, its greenish color at RT is assigned to an O(2-) → Fe(3+) ligand-to-metal charge transfer at 2.57 eV coupled with d-d transitions peaking at 1.35 and 2.04 eV. When the temperature is raised, YIG displays a marked thermochromic effect; i.e., the color changes continuously from greenish to brownish, which offers opportunities for potential application as a temperature indicator for everyday uses. The origin of the observed thermochromism is assigned to a gradual red shift of the ligand-to-metal charge transfer with temperature while the positioning in energy of the d-d transitions is almost unaltered. Attempts to achieve more saturated colors via doping (e.g., Al(3+), Ga(3+), Mn(3+), ...) remained unsuccessful except for chromium. Indeed, Y3Fe5O12:Cr samples exhibit at RT the same color than the undoped garnet at 200 °C. The introduction of Cr(3+) ions strongly impacts the color of the Y3Fe5O12 parent either by an inductive effect or, more probably, by a direct effect on the electronic structure of the undoped material with formation of a midgap state. PMID:25382733

  12. Micromachining of Ti-3Al-2.5V tubes by nanosecond Nd:YAG laser

    Science.gov (United States)

    Lin, Yaomin; Gupta, Mool C.

    2013-03-01

    Laser micromachining is one of many laser material processing technologies employed in scientific research and engineering applications. It involves the deposition of photon energy and the material interaction. The intense photothermal energy is transported into the target material causing melting and evaporation. The material is removed layer by layer by melting and flowing away or by direct vaporization / ablation. It is due to the focused small spot size that the laser micromachining can remove material in small quantity at a time, thus precise control of geometrical dimension is possible. In this work, a nanosecond pulsed Nd:Yttrium-Aluminum-Garnet (Nd:YAG) laser was employed to generate relatively long notch of different dimensions (25.4 mm-length × 0.1 mm-width × 0.051/0.102/0.152 mmdepth) on Ti-3Al-2.5V seamless tubes for fatigue life study. Cyclic hydraulic impulse pressure test was conducted to find out the fatigue limits of the titanium tube containing the laser micromachined notch. The results of fatigue lives, crack profile and pattern of crack propagation are presented and discussed in this paper. Scanning electron microscopy was employed to characterize the fatigue crack profile and the laser micronotch. The capability of generating sharper notch root and consistent pre-crack on the surface of materials makes nanosecond pulsed Nd:YAG laser a great choice in preparing for fatigue test samples for crack growth life study.

  13. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    Energy Technology Data Exchange (ETDEWEB)

    Genin, F.Y.; Michlitsch, K.; Furr, J.; Kozlowski, M.R.; Krulevitch, P.

    1997-01-01

    1-{mu}m thick circular dots, 10-250 {mu}m dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions.

  14. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    International Nuclear Information System (INIS)

    1-μm thick circular dots, 10-250 μm dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions

  15. Experimental and numerical research on shock initiation of pentaerythritol tetranitrate by laser driven flyer plates

    International Nuclear Information System (INIS)

    The unconfined fine grain pentaerythritol tetranitrate explosive columns whose size of φ5x5 mm2 and density of 1.2 g/cm3 were impacted and initiated by laser driven flyers launched from substrate backed aluminum films. The flyers were driven by single pulse from a Q-switched Nd:YAG (yttrium aluminum garnet) laser. The aluminum flyer plates were 5.5 and 10 μm in thickness, and had diameters of ∼1 mm. The induced stress in samples was intense but of only nanosecond duration. The initiation threshold of the explosive under such short pressure pulse (3.8 ns) was obtained in experiments as 7.1±0.2 GPa. The whole process of initiation had been simulated successfully using one-dimensional Lagrange hydrodynamic code SSS and a forest fire burn technique had been used in the simulation. The pressure and reaction fraction of explosive during the initiation process have been obtained and the theoretical results may be 20% higher than that of experiments

  16. Laser lift-off technique for freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN and its application to light-emitting diodes

    International Nuclear Information System (INIS)

    We developed a laser lift-off technique for a freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN. A combination of an In droplet formed by thermal decomposition of GaInN during growth and a pulsed second-harmonic neodymium-doped yttrium aluminum garnet laser (λ = 532 nm) realized the lift-off GaN substrate. After laser lift-off of the GaN substrate, it was used to achieve 380 nm ultraviolet light-emitting diodes with light output enhanced 1.7-fold. In this way, the light extraction can be improved by removing the GaN substrate.

  17. Magneto-Optical Experiments on Rare Earth Garnet Films.

    Science.gov (United States)

    Tanner, B. K.

    1980-01-01

    Describes experiments in which inexpensive or standard laboratory equipment is used to measure several macroscopic magnetic properties of thin rare earth garnet films used in the manufacture of magnetic bubble devices. (Author/CS)

  18. Facial scars after a road accident--combined treatment with pulsed dye laser and Q-switched Nd:YAG laser.

    Science.gov (United States)

    Martins, Andréa; Trindade, Felicidade; Leite, Luiz

    2008-09-01

    We report the case of a woman who presented with several facial scars following a road accident. Treatment was carried out using combined laser treatment with pulsed dye laser (PDL) and Q-switched neodymium:yttrium-aluminum-garnet laser (QS Nd:YAG laser). No side effects or complications from treatment were noted or reported. The patient had very good cosmetic results with this combined technique. A variety of facial scars - erythematous, pigmented, atrophic, and hypertrophic - may occur as a result of trauma, surgery, burns, and skin disease. Surgery with other adjunctive methods including radiotherapy, intralesional steroids, and pressure therapy have shown variable results. Laser treatment has been attempted for scar revision since the 1980s. The PDL is the optimal treatment for reducing scar bulk and symptoms. It also decreases erythema and telangiectasia associated with scars, normalizes the skin surface texture, and improves the scar pliability. The QS Nd:YAG laser (1064 nm) is highly effective for traumatic tattoo removal, resulting in complete clearance in the majority of cases. PMID:18789060

  19. Indus Basin sediment provenance constrained using garnet geochemistry

    Science.gov (United States)

    Alizai, Anwar; Clift, Peter D.; Still, John

    2016-08-01

    The chemical and mineralogical diversity of western Himalayan rivers is the result of each of them draining different tectonic and lithologic units, whose character is partly transferred to the sediments carried by those rivers. Garnet geochemistry was employed to discriminate provenance in the Indus River system. We characterized the geochemistry of garnet sediment grains from the modern Indus and all its major tributaries, as well as the related but ephemeral Ghaggar-Hakra River and dune sand from the Thar Desert. Garnet geochemistry displays a unique signature for the Himalayan rivers on the east of the Indus drainage compared to those in the western drainage. The trunk Indus remains distinct because of the dominant arc-type pyrope-garnet derived from Kohistan and the Karakoram. The Jhellum, which lies just east of the modern Indus has modest concentrations of arc-type pyrope garnets, which are more depleted in the other eastern tributaries. Their presence in the Jhellum reflects recycling of trunk Indus garnets through the Miocene Siwalik Group foreland sedimentary rocks. The Thar Desert dune sample contains significant numbers of grains similar to those in the trunk Indus, likely reworked by monsoon winds from the SW. Our data further indicate the presence of a Himalayan river channel east of the present Indus, close to the delta, in the Nara River valley during the middle Holocene. Sands from this channel cannot be distinguished from the Indus on the basis of their garnet geochemistry alone but we favour their sedimentation from an Indus channel rather than reworking of desert sands by another stream. The garnet geochemistry shows some potential as a provenance tool, but cannot be used alone to uniquely discriminate Indus Basin provenance.

  20. Garnets from the Camafuca-Camazambo kimberlite (Angola

    Directory of Open Access Journals (Sweden)

    Correia Eugénio A.

    2006-01-01

    Full Text Available This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004 and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10 and Ca-saturated (G9 garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa. The occurrence of diamond stability field garnets (G10D is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

  1. Application of YAG laser cladding to the flange seating surface

    International Nuclear Information System (INIS)

    Stainless cladding on carbon steel is usually conducted by shielded metal arc welding (SMAW) or gas tungsten arc welding (GTAW). YAG ( Yttrium-Aluminum-Garnet) laser welding is superior to these methods of welding in the following respects : (1) The heat affected zone (HAZ) is narrower and there is less distortion. (2) YAG laser cladding has the required chemical compositions, even with possibly fewer welding layers under controlled dilution. (3) Greater welding speed. YAG laser cladding application to vessel flange seating surfaces was examined in this study and the results are discussed. The following objectives were carried out : (1) Determination of welding conditions for satisfactory cladding layers and (2) whether cladding would be adequately possible at a cornered section of a stair-like plate, assuming actual flange shape. (3) Measurement of welding distortion and heat affected zone in carbon steel. The welding conditions for producing no-crack deposit with low dilution in carbon steel were clarified and welding by which cladding at cornered section would be possible was achieved. welding distortion by YAG laser was found less than with GTAW and HAZ made by first layer welding could be tempered appropriately by second layer welding. (author)

  2. Calcium and lithium ion production for laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, M., E-mail: okamura@bnl.gov [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Palm, K. [Department of Physics, Cornell University, Ithaca, New York 14853-2501 (United States); Stifler, C. [Engineering Physics Systems Department, Providence College, Providence, Rhode Island 02918 (United States); Steski, D.; Kanesue, T. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ikeda, S. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa (Japan); Kumaki, M. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Research Institute for Science and Engineering, Waseda University, Tokyo (Japan)

    2016-02-15

    Calcium and lithium ion beams are required by NASA Space Radiation Laboratory at Brookhaven National Laboratory to simulate the effects of cosmic radiation. To identify the difficulties in providing such highly reactive materials as laser targets, both species were experimentally tested. Plate shaped lithium and calcium targets were fabricated to create ablation plasmas with a 6 ns 1064 nm neodymium-doped yttrium aluminum garnet laser. We found significant oxygen contamination in both the Ca and Li high charge state beams due to the rapid oxidation of the surfaces. A large spot size, low power density laser was used to create low charge state beams without scanning the targets. The low charge state Ca beam did not have any apparent oxygen contamination, showing the potential to clean the target entirely of oxide with a low power beam once in the chamber. The Li target was clearly still oxidizing in the chamber after each low power shot. To measure the rate of oxidation, we shot the low power laser at the target repeatedly at 10 s, 30 s, 60 s, and 120 s interval lengths, showing a linear relation between the interval time and the amount of oxygen in the beam.

  3. Calcium and lithium ion production for laser ion source

    International Nuclear Information System (INIS)

    Calcium and lithium ion beams are required by NASA Space Radiation Laboratory at Brookhaven National Laboratory to simulate the effects of cosmic radiation. To identify the difficulties in providing such highly reactive materials as laser targets, both species were experimentally tested. Plate shaped lithium and calcium targets were fabricated to create ablation plasmas with a 6 ns 1064 nm neodymium-doped yttrium aluminum garnet laser. We found significant oxygen contamination in both the Ca and Li high charge state beams due to the rapid oxidation of the surfaces. A large spot size, low power density laser was used to create low charge state beams without scanning the targets. The low charge state Ca beam did not have any apparent oxygen contamination, showing the potential to clean the target entirely of oxide with a low power beam once in the chamber. The Li target was clearly still oxidizing in the chamber after each low power shot. To measure the rate of oxidation, we shot the low power laser at the target repeatedly at 10 s, 30 s, 60 s, and 120 s interval lengths, showing a linear relation between the interval time and the amount of oxygen in the beam

  4. Calcium and lithium ion production for laser ion source

    Science.gov (United States)

    Okamura, M.; Palm, K.; Stifler, C.; Steski, D.; Ikeda, S.; Kumaki, M.; Kanesue, T.

    2016-02-01

    Calcium and lithium ion beams are required by NASA Space Radiation Laboratory at Brookhaven National Laboratory to simulate the effects of cosmic radiation. To identify the difficulties in providing such highly reactive materials as laser targets, both species were experimentally tested. Plate shaped lithium and calcium targets were fabricated to create ablation plasmas with a 6 ns 1064 nm neodymium-doped yttrium aluminum garnet laser. We found significant oxygen contamination in both the Ca and Li high charge state beams due to the rapid oxidation of the surfaces. A large spot size, low power density laser was used to create low charge state beams without scanning the targets. The low charge state Ca beam did not have any apparent oxygen contamination, showing the potential to clean the target entirely of oxide with a low power beam once in the chamber. The Li target was clearly still oxidizing in the chamber after each low power shot. To measure the rate of oxidation, we shot the low power laser at the target repeatedly at 10 s, 30 s, 60 s, and 120 s interval lengths, showing a linear relation between the interval time and the amount of oxygen in the beam.

  5. Fractional 532-nm Q-switched Nd:YAG laser: One of the safest novel treatment modality to treat café-au-lait macules.

    Science.gov (United States)

    Won, Kwang Hee; Lee, Ye Jin; Rhee, Do Young; Chang, Sung Eun

    2016-10-01

    Café-au-lait macules (CALMs) are benign epidermal basilar hyperpigmentations that can be found in an isolated form or in association with neurocutaneous syndromes. Frequency-doubled Q-switched neodymium-doped yttrium aluminum garnet laser (532-nm QSNYL) does not penetrate deeply into the skin and is therefore suitable for epidermal pigmented lesion. Fractional photothermolysis (FP) targets only very small areas of the skin, without injuring adjacent areas of healthy, normal skin. Herein, we report a case of CALMs successfully treated with fractional 532-nm QSNYL. By applying FP to 532-nm QSNYL, we could treat CALMs safely with less downtime as compared to conventional laser treatments and expect more energy delivery for each microscopic hole, thereby allowing higher response rate. PMID:26962881

  6. Garnet: a key to unraveling Earth's dynamic lithosphere

    Science.gov (United States)

    Smit, M. A.; Scherer, E. E.; Mezger, K.; Lee, J.; Ratschbacher, L.; Kooijman, E.; Stearns, M. A.

    2015-12-01

    Garnet enables constraints on all parameters relevant to lithosphere studies: pressure, temperature, strain, and time. This aspect, in combination with its widespread occurrence in metamorphic rocks and ability to resist retrogression, make the mineral a prime target in research into the dynamics of mountain belts. Garnet-based petrological and geochemical tools have diversified and improved as a result of recent advancements in spatial and analytical resolution. In particular, our ability to obtain precise age constraints using garnet Lu-Hf and Sm-Nd geochronology, and interpret these in a geological context has greatly improved. This contribution highlights a series of recent enhancements to the garnet toolkit and demonstrates its versatility in two case studies set in an archetypal collisional orogen: the Pamir-Himalaya-Tibet mountain chain. To enable a more effective use of garnet geochronology, we investigated the retentiveness of Lu-Hf and Sm-Nd isotope signatures in naturally metamorphosed garnet. Diffusive re-equilibration of these signatures is shown to occur to a minor, if not insignificant, extent during crustal metamorphism, thus firmly establishing these methods as reliable geochronometers. Diffusive major-element zoning analysis of the same garnet led to the development of a new thermometric tool, which was shown to provide reliable temperature estimates for a wide variety of rocks and terranes. We used Lu-Hf garnet geochronology to show that mid-crustal flow and 'Barrovian-type' metamorphism of rocks now exposed in the North Himalayan Gneiss Domes in Central Tibet commenced in the early Eocene. This result is the first to confirm that crustal thickening and contraction in the Tibetan Himalaya was broadly synchronous with the collision between Greater India and Eurasia. Garnet dating and thermometry, and rutile U-Pb thermochronology in the Pamir revealed a history of heating to 750-830 °C, commencing at 37 Ma in the South Pamir and occurring

  7. Multistep sintering to synthesize fast lithium garnets

    Science.gov (United States)

    Xu, Biyi; Duan, Huanan; Xia, Wenhao; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-01-01

    A multistep sintering schedule is developed to synthesize Li7La3Zr2O12 (LLZO) doped with 0.2 mol% Al3+. The effect of sintering steps on phase, relative density and ionic conductivity of Al-doped LLZO has been evaluated using powder X-Ray diffraction (XRD), scanning electron microscopy (SEM), 27Al magic spinning nuclear magnetic resonance (NMR) spectroscopy and electrochemical impedance spectroscopy (EIS). The results show that by holding the sample at 900 °C for 6 h, the mixture of tetragonal and cubic garnet phases are obtained; by continuously holding at 1100 °C for 6 h, the tetragonal phase completely transforms into cubic phase; by holding at 1200 °C, the relative density increases without decomposition of the cubic phase. The Al-LLZO pellets after multistep sintering exhibit cubic phase, relative density of 94.25% and ionic conductivity of 4.5 × 10-4 S cm-1 at room temperature. Based on the observation, a sintering model is proposed and discussed.

  8. Laser angioplasty using a lensed-fiber delivery system and a pulsed Nd:YAG laser: early clinical results

    Science.gov (United States)

    White, Christopher J.; Ramee, Stephen R.; Mesa, Juan E.; Hollier, Larry H.; Murgo, Joseph P.; Aita, Michael; Samson, Gene; Godfrey, Maureen A.

    1990-07-01

    We performed a clinical trial to evaluate the safety and efficacy of a unique lensed-fiber delivery system with a pulsed Neodymium-yttrium aluminum garnet (Nd-YAG) laser in patients with atherosclerotic peripheral vascular disease. The lensed-fiber consists of a spherical silica lens, 1 .5 mm in diameter, mounted at the distal tip of a 300 im silica optical fiber. The Nd-YAG laser is pulsed at 10 Hz, and we delivered 0.5 J/pulse with a pulse duration of 100 msecs in 2- to 5-second bursts. Successful recanalization of stenoses or occlusions was obtained in 9 of 10 patients and was manifested by improvement in blood flow as measured angiographically and with ankle-brachial blood pressure index improvement (> 0. 15). There were no arterial perforations or dissections associated with the laser angioplasty. All successfully recanalized patients required adjunctive balloon angioplasty to obtain a satisfactory reduction in luminal diameter stenosis of the treated artery. We conclude that this unique delivery system and the pulsed Nd-YAG laser are a safe and effect method of recanalizing arterial stenoses not amenable to conventional balloon angioplasty alone.

  9. Structure and thermodynamics of uranium-containing iron garnets

    Science.gov (United States)

    Guo, Xiaofeng; Navrotsky, Alexandra; Kukkadapu, Ravi K.; Engelhard, Mark H.; Lanzirotti, Antonio; Newville, Matthew; Ilton, Eugene S.; Sutton, Stephen R.; Xu, Hongwu

    2016-09-01

    Use of crystalline garnet as a waste form phase appears to be advantageous for accommodating actinides from nuclear waste. Previous studies show that large amounts of uranium (U) and its analogues such as cerium (Ce) and thorium (Th) can be incorporated into the garnet structure. In this study, we synthesized U loaded garnet phases, Ca3UxZr2-xFe3O12 (x = 0.5-0.7), along with the endmember phase, Ca3(Zr2)SiFe3+2O12, for comparison. The oxidation states of U were determined by X-ray photoelectron and absorption spectroscopies, revealing the presence of mixed pentavalent and hexavalent uranium in the phases with x = 0.6 and 0.7. The oxidation states and coordination environments of Fe were measured using transmission 57Fe-Mössbauer spectroscopy, which shows that all iron is tetrahedrally coordinated Fe3+. U substitution had a significant effect on local environments, the extent of U substitution within this range had a minimal effect on the structure, and unlike in the x = 0 sample, Fe exists in two different environments in the substituted garnets. The enthalpies of formation of garnet phases from constituent oxides and elements were first time determined by high temperature oxide melt solution calorimetry. The results indicate that these substituted garnets are thermodynamically stable under reducing conditions. Our structural and thermodynamic analysis further provides explanation for the formation of natural uranium garnet, elbrusite-(Zr), and supports the potential use of Ca3UxZr2-xFe3O12 as viable waste form phases for U and other actinides.

  10. Continuous-wave dual-wavelength Nd:YAG laser operation at 1319 and 1338 nm

    Science.gov (United States)

    Sun, G. C.; Lee, Y. D.; Zao, Y. D.; Xu, L. J.; Wang, J. B.; Chen, G. B.; Lu, J.

    2013-04-01

    We report an efficient continuous-wave (CW) dual-wavelength operation of an Nd:YAG (YAG: yttrium aluminum garnet) laser at 1319 and 1338 nm. An output power of 2.47 W for the dual-wavelength operation was achieved at the incident pump power of 16.7 W. Intracavity sum-frequency mixing at 1319 and 1338 nm was then realized in an LBO (lithium triborate) crystal to reach the red range. A maximum output power of 879 mW in the red spectral range at 664 nm has been achieved. The red output stability is better than 3.4%. The red beam quality M2 values are about 1.21 and 1.35 in the horizontal and vertical directions respectively.

  11. Nd:YAG Laser Posterior Capsulotomy and Visual Outcome

    Directory of Open Access Journals (Sweden)

    Khaleda Nazneen Bari

    2013-05-01

    Full Text Available Background: Neodymium-doped yttrium aluminum garnet (Nd:YAG laser capsulotomy is a relatively noninvasive procedure that is used in the treatment of posterior capsular opacification (PCO. PCO is caused by proliferation of lens epithelial cells which causes fibrotic changes and wrinkling of the posterior capsule and results in decreased vision, glare, and other symptoms similar to that of the original cataract.Objective: To find out the visual outcome after performing Nd:YAG laser capsulotomy for PCO.Materials and method: A prospective clinical trial was carried out in National Institute of Ophthalmology (NIO, Dhaka, Bangladesh from January 2010 to June 2011 on purposively selected 70 adult subjects of both sexes who developed PCO within 2 months to more than 2 years after extracapsular cataract extraction with posterior chamber intra ocular lens implant. After thorough pre laser assessment Nd:YAG laser capsulotomy was carried out with Zeis VISULAS YAG II through Zeiss slit lamp under topical anesthesia. Data were recorded and expressed as proportion.Results: Out of the 70 subjects 40 were male and 30 were female. The average time interval of cataract surgery and Nd: YAG laser capsulotomy was 23 months. Capsular fibrosis (57.04% was the predominant type of PCO. The pre laser visual acuity (VA of more than 61.06% of eyes was 6/36 or below while 41.12% had VA hand movements to finger count. After Nd:YAG laser capsulotomy VA of 6/18 or better was achieved in 63.9% of eyes while 9.94% recovered to 6/9 and 11.36% achieved 6/6. None of these eyes showed further deterioration in VA.Conclusion: Nd:YAG laser capsulotomy for PCO is safe, effective and a rewarding procedure for improvement of vision.

  12. Fabrication, characterisation and magneto-optical enhancement of thin film BiGa:Dy iron garnet

    International Nuclear Information System (INIS)

    This thesis describes the production of BiGa:Dy Iron garnet thin films by the processes of both pulsed laser deposition and r.f. magnetron sputtering. High quality films with large magneto-optical effects, perpendicular magnetic anisotropy, square hysteresis loops and smooth surfaces with small grain size have been produced by both methods from the same Bi2.3Dy0.8Fe4.0Ga0.9O12 target. The optimised PLD conditions required to produce films of maximum MO activity onto GGG(111) substrates included a substrate temperature of 590 deg. C and an oxygen pressure of 0.2mbar. Film composition exhibited the same stoichiometry as the target material. The films produced by r.f. magnetron sputtering displayed a low bismuth content, compared to those of the PLD films. Optimised conditions, including a post annealing temperature of 690 deg. C and an argon pressure of 0.04mbar, produced films of composition Bi1.2Dy1.3Fe4.4Ga1.1O12. Optical and MO characterisation of both types of film, in terms of the intrinsic complex refractive index (n) and Voigt parameter (Q), throughout the visible region, revealed the increased Bi content harvested from the PLD process led to significantly larger optical absorption and MO effects. However, the sputtering technique produced films with superior surface quality, and film uniformity over a larger area. The optical and MO characterisation enabled the design and fabrication of multilayer enhancement structures to maximise the Kerr rotation, whilst minimising the Kerr ellipticity for a given reflectance value at a chosen wavelength. Large MO enhancement proved possible towards higher wavelengths ( > 500nm) where the absorption of the garnet was low, despite the much lower intrinsic MO activity displayed at these wavelengths. Temperature dependence measurements, carried out on garnet films, revealed that compensation temperature was very sensitive to film composition, and in particular, bismuth content. (author)

  13. Dating Subduction Zone Metamorphism with Garnet and Lawsonite Geochronology

    Science.gov (United States)

    Mulcahy, S. R.; Vervoort, J. D.

    2013-12-01

    Lawsonite [CaAl2Si2O7(OH)2 H2O] is a critical index mineral for high- to ultrahigh-pressure metamorphism associated with subduction. Lawsonite is an important carrier of water into the mantle, a likely contributor to subduction zone seismicity, and a bearer of trace elements that link metamorphism to arc magmatism. Due to its limited pressure-temperature stability, lawsonite can serve as a powerful petrogenetic indicator of specific metamorphic events. Lu-Hf dating of lawsonite, therefore provides a potentially powerful new tool for constraining subduction zone processes in a pressure-temperature window where few successful geochronometers exist. Broad application of lawsonite Lu-Hf geochronology requires constraining the role of pressure-temperature path, lawsonite forming reactions, and the Lu and Hf systematics within lawsonite and other blueschist facies minerals. We are working to address the role of the metamorphic path on the applicability of lawsonite Lu-Hf geochronology within the Franciscan Complex of California. The Franciscan Complex preserves mafic high-grade exotic blocks in melange that underwent a counterclockwise pressure-temperature path wherein garnet, which strongly partitions heavy rare-earth elements, formed prior to lawsonite. Coherent mafic rocks within the Franciscan Complex, however, underwent a clockwise pressure-temperature path and lawsonite growth occurred prior to garnet. We sampled exotic blocks of garnet-hornblendite, garnet-epidote amphibolite, garnet-epidote blueschist, and lawsonite blueschist from the Berkeley Hills and Tiburon Peninsula of California. We collected four samples from coherent lawsonite blueschist across the lawsonite-pumpellyite-epidote isograds in Ward Creek, near Cazadero California. High-grade blocks give ages similar to existing Franciscan geochronology: multi-stage garnet in hornblendite gives the following ages: 171×1.3 Ma (MSWD 2.8) for the core and 159.4×0.9 Ma (MSWD 2.0) for the corresponding rim; 166

  14. Electron microscopy of compound oxide laser materials

    Science.gov (United States)

    Eakins, Daniel E.; LeBret, Joel B.; Norton, M. G.; Bahr, David F.; Dumm, John Q.

    2003-06-01

    Oxide single crystals, such as yttrium aluminum garnet (YAG) and yttrium orthovanadate (YVO4), are important host crystals for solid-state laser applications. These crystals are often grown by the Czochralski process and are doped with neodymium during growth. The microstructure of the resultant crystal affects the overall laser performance and it is necessary to be able to characterize grown-in defects in the material. Scanning electron microscopy has been used to examine the fracture surfaces of YAG and has shown the presence of microscopic voids, which act as stress concentrators and in some cases appear to be the cause of fracture. Transmission electron microscopy (TEM) has been used to characterize various defects in both YAG and YVO4 crystals. The defects found depend on the growth conditions, specifically the Nd concentration in the crystal and the position within the boule. One of the most common defects identified in both materials were microscopic spherical particles. In YAG these particles appeared to be located primarily in the core regions and analysis of high resolution images indicate that they are due to regions that are both compositionally and orientationally different from the matrix phase. Direct observation of dislocations in YVO4 was made using TEM. In YAG only indirect evidence for dislocations could be found from the observation of river marks on fracture surfaces.

  15. Thermally induced transparency for short spin wave pulses in yttrium iron garnet (YIG) films

    Science.gov (United States)

    Ordonez Romero, Cesar Leonardo; Kolokoltsev, Oleg; Gomez Arista, Ivan; Qureshi, Naser; Monsiváis Galindo, Guillermo; Vargas Hernández, Hesiquio

    2014-03-01

    The compensation of spin wave propagation losses plays a very important role in the development of novel magnonic devices. Up to now, however, most of the known amplification methods present relative narrow frequency bandwidths due to their resonant nature. In this work, we present compensation of the propagation losses or pseudo-amplification of travelling spin waves by tailoring the bias magnetic field profile. The thermally-induced non-uniform profile of the magnetization introduced on an Yttrium Iron Garnet (YIG) thin film by a localized spot of a cw argon-ion laser creates the conditions to observe the complete compensation of the spin wave propagation losses. The spin wave evolution was mapped with a time and spaced resolved inductive magneto-dynamic prove system. The experiment was carried out using a uniform sample of single-crystal YIG film grown on a gallium-gadolinium garnet (GGG) substrate. The 2mm-wide, 20mm-long and 6microns-thick YIG strip was saturated with an external magnetic field enabling the set up for the propagation of magneto-static surface waves. This work was supported by the UNAM-DGAPA-PAPIIT IA100413.

  16. Induced magnetism in exfoliated graphene via proximity effect with yttrium iron garnet thin films

    Science.gov (United States)

    Amado, Mario; Li, Yang; di Bernardo, Angelo; Lombardo, Antonio; Ferrari, Andrea C.; Robinson, Jason

    The recent discovery of the quantum anomalous Hall effect (QAHE) in magnetically doped topological insulators cooled below in the milikelvin regime represents breakthrough in the field of spintronics. Theoretically, the QAHE should occur in graphene proximity coupled to a ferromagnetic insulato but with the promise of much higher operating temperatures for practical applications. Hints of proximity-induced magnetism in graphene coupled to yttrium iron garnet (YIG) films have been reported although the QAHE remains unobserved; the lack of a fully developed plateau in graphene/YIG devices can be attributed to poor interfacial coupling and therefore a dramatically reduced magnetic proximity effect. Here we report the deposition and characterisation of epitaxial thin-films of YIG on lattice-matched gadolinium gallium garnet substrates by pulsed laser deposition. Pristine exfoliated graphene flakes transferred mechanically onto the YIG are reported alongside results that correlate the effects of YIG morphology on the electronic and crystal properties of graphene by electrical (low temperature magnetoresistance measurements in Hall-bar-like configuration) and optical (Raman) means.

  17. Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

    Science.gov (United States)

    Benafan, O.; Chen, S.-Y.; Kar, A.; Vaidyanathan, R.

    2015-12-01

    Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell's equations and heat conduction.

  18. Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

    Energy Technology Data Exchange (ETDEWEB)

    Benafan, O., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu; Vaidyanathan, R., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu [Advanced Materials Processing and Analysis Center (AMPAC), Materials Science and Engineering, Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Chen, S.-Y.; Kar, A. [Laser-Advanced Materials Processing Laboratory, Center for Research and Education in Optics and Lasers (CREOL), College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States)

    2015-12-15

    Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell’s equations and heat conduction.

  19. Facial scars after a road accident: combined treatment with PDL and Q-switched ND:YAG laser.

    Science.gov (United States)

    Martins, Andrea; Trindade, Felicidade; Leite, Luiz

    2008-09-01

    We report the case of a woman who presented with several facial scars following a road accident. Treatment was carried out using combined laser treatment with pulsed dye laser (PDL) and the Q-switched neodymium:yttrium-aluminum-garnet laser (QS Nd:YAG laser). No side effects or complications from treatment were noted or reported. The patient had very good cosmetic results with this combined technique. A variety of facial scars--erythematous, pigmented, atrophic and hypertrophic--may occur as a result of trauma, surgery, burns and skin disease. Surgery with other adjunctive methods including radiotherapy, intralesional steroids and pressure therapy has shown variable results. Laser treatment has been attempted for scar revision since the 1980s. The PDL is the optimal treatment for reducing scar bulk and symptoms. It also decreases the erythema and telangiectasia associated with scars, normalizes the skin surface texture and improves scar pliability. The QS Nd:YAG laser (1064 nm) is highly effective for traumatic tattoo removal, resulting in complete clearance in the majority of cases. PMID:18608707

  20. Treatment of urethral diseases with neodymium:YAG laser.

    Science.gov (United States)

    Bloiso, G; Warner, R; Cohen, M

    1988-08-01

    Over a thirty-month period, a wide variety of common urethral problems were treated on an ambulatory basis, with the neodymium:yttrium-aluminum garnet (Nd:YAG) laser. When used discriminately, laser treatment appears to be an effective modality for the management of selected urethral strictures. Thus far, excellent results have been obtained in 30 of 31 cases of short strictures where laser urethrotomy was performed as the first stricture procedure (average follow-up 10 months). Furthermore, in a series of 36 cases of secondary bladder neck contractures, all of the evaluated patients responded well (average follow-up 7 months). Good results were obtained in only 11 of 48 complicated strictures (average follow-up 14 months). However, while most of these extensive strictures were not eradicated, laser therapy generally produced a documented clinical improvement, comparable to urethrotomy or dilatation, in 15 of these cases. A series of 24 condylomata involving the urethra were treated satisfactorily, with no recurrences (average follow-up 13 months). Laser treatment also has been used successfully for the management of several urethral caruncles, urethral polyps, two meatal hemangiomas, one urethral carcinoma, and a distal duplicated urethra. Recently, the Nd:YAG laser has been applied to the prostatic urethra with vaporization of obstructing median bar hyperplasia. Favorable results have been achieved in 5 of 6 cases treated with a newly developed technique that utilizes direct laser contact. Retrograde ejaculation has not been encountered in these patients (average follow-up 6 months). All of these procedures have been accomplished in the office, largely without urethral catheterization. Lidocaine jelly occasionally supplemented with intravenous sedation provided satisfactory anesthesia. PMID:3400132